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Error Handling and Diagnostics


An application program must anticipate runtime errors and attempt to recover from them. This chapter provides an in-depth discussion of error reporting and recovery. You learn how to handle warnings and errors using the status variables SQLCODE, SQLSTATE, and SQLCA (SQL Communications Area), and the WHENEVER statement. You also learn how to diagnose problems using the status variable ORACA (Oracle Communications Area). The following topics are discussed:

The Need for Error Handling

A significant part of every application program must be devoted to error handling. The main benefit of error handling is that it allows your program to continue operating in the presence of errors. Errors arise from design faults, coding mistakes, hardware failures, invalid user input, and many other sources

You cannot anticipate all possible errors, but you can plan to handle certain kinds of errors meaningful to your program. For the Oracle Precompilers, error handling means detecting and recovering from SQL statement execution errors.

You can also prepare to handle warnings such as "value truncated" and status changes such as "end of data." It is especially important to check for error and warning conditions after every data manipulation statement, because an INSERT, UPDATE, or DELETE statement might fail before processing all eligible rows in a table.

Error Handling Alternatives

The Oracle Precompilers provide four status variables that serve as error handling mechanisms:

The MODE option (described [*]) governs ANSI/ISO compliance. The availability of the SQLCODE, SQLSTATE, and SQLCA variables depends on the MODE setting. You can declare and use the ORACA variable regardless of the MODE setting. For more information, see "Using the Oracle Communications Area" [*].

When MODE={ORACLE|ANSI13}, you must declare the SQLCA status variable. SQLCODE and SQLSTATE declarations are accepted (not recommended) but are not recognized as status variables. For more information, see "Using the SQL Communications Area" [*].

When MODE={ANSI|ANSI14}, you can use any one, two, or all three of the SQLCODE, SQLSTATE, and SQLCA variables. To determine which variable (or variable combination) is best for your application, see "Using Status Variables when MODE={ANSI|ANSI14}" [*].

SQLCODE and SQLSTATE

With Release 1.5 of the Oracle Precompilers, the SQLCODE status variable was introduced as the SQL89 standard ANSI/ISO error reporting mechanism. The SQL92 standard listed SQLCODE as a deprecated feature and defined a new status variable, SQLSTATE (introduced with Release 1.6 of the Oracle Precompilers), as the preferred ANSI/ISO error reporting mechanism.

SQLCODE stores error codes and the "not found" condition. It is retained only for compatibility with SQL89 and is likely to be removed from future versions of the standard.

Unlike SQLCODE, SQLSTATE stores error and warning codes and uses a standardized coding scheme. After executing a SQL statement, the Oracle server returns a status code to the SQLSTATE variable currently in scope. The status code indicates whether a SQL statement executed successfully or raised an exception (error or warning condition). To promote interoperability (the ability of systems to exchange information easily), SQL92 predefines all the common SQL exceptions.

SQLCA

The SQLCA is a record-like, host-language data structure. Oracle updates the SQLCA after every executable SQL statement. (SQLCA values are undefined after a declarative statement.) By checking Oracle return codes stored in the SQLCA, your program can determine the outcome of a SQL statement. This can be done in two ways:

You can use WHENEVER statements, code explicit checks on SQLCA variables, or do both. Generally, using WHENEVER statements is preferable because it is easier, more portable, and ANSI-compliant.

ORACA

When more information is needed about runtime errors than the SQLCA provides, you can use the ORACA, which contains cursor statistics, SQL statement data, option settings, and system statistics.

The ORACA is optional and can be declared regardless of the MODE setting. For more information about the ORACA status variable, see "Using the Oracle Communications Area" [*].

Using Status Variables when MODE={ANSI|ANSI14}

When MODE={ANSI|ANSI14}, you must declare at least one -- you may declare two or all three -- of the following status variables:

In Pro*COBOL, you cannot declare SQLCODE if SQLCA is declared. Likewise, you cannot declare SQLCA if SQLCODE is declared. The field in the SQLCA data structure that stores the error code for Pro*COBOL is also called SQLCODE, so errors will occur if both status variables are declared.

Your program can get the outcome of the most recent executable SQL statement by checking SQLCODE and/or SQLSTATE explicitly with your own code after executable SQL and PL/SQL statements. Your program can also check SQLCA implicitly (with the WHENEVER SQLERROR and WHENEVER SQLWARNING statements) or it can check the SQLCA variables explicitly.

Note: When MODE={ORACLE|ANSI13}, you must declare the SQLCA status variable. For more information, see "Using the SQL Communications Area" [*].

Some Historical Information

The treatment of status variables and variable combinations by the Oracle Precompilers has evolved beginning with Release 1.5.

Release 1.5

The Oracle Precompilers, Release 1.5, presumed there was a status variable SQLCODE whether or not it was declared in a Declare Section; in fact, the precompiler never bothered to note whether there was a declaration for SQLCODE or not -- it just presumed one existed. SQLCA would be used as a status variable if and only if there was an INCLUDE of the SQLCA.

Release 1.6

Beginning with Oracle Precompilers, Release 1.6, the precompilers no longer presume that there is a SQLCODE status variable and it is not required. The precompiler requires that at least one of SQLCA, SQLCODE, or SQLSTATE be declared.

SQLCODE is recognized as a status variable if and only if at least one of the following criteria is satisfied:

If the precompiler finds a SQLSTATE declaration (of exactly the right type of course) in a Declare Section or finds an INCLUDE of the SQLCA, it will not presume SQLCODE is declared.

Release 1.7

Because Release 1.5 of the Oracle Precompilers allowed the SQLCODE variable to be declared outside of a Declare Section while also declaring SQLCA, precompilers Release 1.6 and greater are presented with a compatibility problem. A new option, ASSUME_SQLCODE={YES|NO} (default NO), was added to fix this in Release 1.6.7 and is documented as a new feature in Release 1.7.

When ASSUME_SQLCODE=YES, and when SQLSTATE and/or SQLCA (Pro*FORTRAN only) are declared as status variables, the precompiler presumes SQLCODE is declared whether or not it is declared in a Declare Section or of the proper type. This causes Releases 1.6.7 and later to act like Release 1.5 in this regard. For information about the precompiler option ASSUME_SQLCODE, see "ASSUME_SQLCODE" [*].

Declaring Status Variables

This section describes how to declare SQLCODE and SQLSTATE. For information about declaring the SQLCA status variable, see "Declaring the SQLCA" [*].

Declaring SQLCODE

SQLCODE (SQLCOD in Pro*FORTRAN) must be declared as a 4-byte integer variable either inside or outside the Declare Section, as shown in Table 8 - 1.

Language SQLCODE Declaration
COBOL SQLCODE PIC S9(9) COMP.
FORTRAN INTEGER*4 SQLCOD
Table 8 - 1. SQLCODE Declarations



If declared outside the Declare Section, SQLCODE is recognized as a status variable if only if ASSUME_SQLCODE=YES. SQLCODE declarations are ignored when MODE={ORACLE|ANSI13}.

Warning: In Pro*COBOL source files, do not declare SQLCODE if SQLCA is declared. Likewise, do not declare SQLCA if SQLCODE is declared. The status variable declared by the SQLCA structure is also called SQLCODE, so errors will occur if both error-reporting mechanisms are used.

With host languages that allow both local and global declarations, you can declare more than one SQLCODE variable. Access to a local SQLCODE is limited by its scope within your program. After every SQL operation, Oracle returns a status code to the SQLCODE currently in scope. So, your program can learn the outcome of the most recent SQL operation by checking SQLCODE explicitly, or implicitly with the WHENEVER statement.

When you declare SQLCODE instead of the SQLCA in a particular compilation unit, the precompiler allocates an internal SQLCA for that unit. Your host program cannot access the internal SQLCA. If you declare the SQLCA and SQLCODE (not supported in Pro*COBOL), Oracle returns the same status code to both after every SQL operation.

Declaring SQLSTATE

SQLSTATE (SQLSTA in Pro*FORTRAN) must be declared as a five-character alphanumeric string inside the Declare Section, as shown in Table 8 - 2. Declaring the SQLCA is optional.

Language SQLSTATE Declaration
COBOL SQLSTATE PIC X(5).
FORTRAN CHARACTER*5 SQLSTA
Table 8 - 2. SQLSTATE Declarations



When MODE={ORACLE|ANSI13}, declarations of the SQLSTATE variable are ignored.

Status Variable Combinations

When MODE={ANSI|ANSI14}, the behavior of the status variables depends on the following:

Table 8 - 3 and Table 8 - 4 describe the resulting behavior of each status variable combination when ASSUME_SQLCODE=NO and when ASSUME_SQLCODE=YES, respectively.

Declare Section (IN/OUT/ --)
SQLCODE SQLSTATE SQLCA
Behavior
OUT -- -- SQLCODE is declared and is presumed to be a status variable.
OUT -- OUT In Pro*COBOL, this status variable configuration is not supported. In Pro*FORTRAN, SQLCA is declared as a status variable, and SQLCODE is declared but is not recognized as a status variable.
OUT -- IN In Pro*COBOL, this status variable configuration is not supported. In Pro*FORTRAN, this status variable configuration is not supported.
OUT OUT -- SQLCODE is declared and is presumed to be a status variable, and SQLSTATE is declared but is not recognized as a status variable.
OUT OUT OUT In Pro*COBOL, this status variable configuration is not supported. In Pro*FORTRAN, SQLCA is declared as a status variable, and SQLCODE and SQLSTATE are declared but are not recognized as status variables.
OUT OUT IN In Pro*COBOL, this status variable configuration is not supported. In Pro*FORTRAN, this status variable configuration is not supported.
OUT IN -- SQLSTATE is declared as a status variable, and SQLCODE is declared but is not recognized as a status variable.
OUT IN OUT In Pro*COBOL, this status variable configuration is not supported. In Pro*FORTRAN, SQLSTATE and SQLCA are declared as status variables, and SQLCODE is declared but is not recognized as a status variable.
OUT IN IN In Pro*COBOL, this status variable configuration is not supported. In Pro*FORTRAN, this status variable configuration is not supported.
IN -- -- SQLCODE is declared as a status variable.
IN -- OUT In Pro*COBOL, this status variable configuration is not supported. In Pro*FORTRAN, SQLCODE and SQLCA are declared as a status variables.
IN -- IN In Pro*COBOL, this status variable configuration is not supported. In Pro*FORTRAN, this status variable configuration is not supported.
IN OUT -- SQLCODE is declared as a status variable, and SQLSTATE is declared but not as a status variable.
IN OUT OUT In Pro*COBOL, this status variable configuration is not supported. In Pro*FORTRAN, SQLCODE and SQLCA are declared as a status variables, and SQLSTATE is declared but is not recognized as a status variable.
IN OUT IN In Pro*COBOL, this status variable configuration is not supported. In Pro*FORTRAN, this status variable configuration is not supported.
IN IN -- SQLCODE and SQLSTATE are declared as a status variables.
IN IN OUT In Pro*COBOL, this status variable configuration is not supported. In Pro*FORTRAN, SQLCODE, SQLSTATE, and SQLCA are declared as a status variables.
IN IN IN In Pro*COBOL, this status variable configuration is not supported. In Pro*FORTRAN, this status variable configuration is not supported.
-- -- -- This status variable configuration is not supported.
-- -- OUT SQLCA is declared as a status variable.
-- -- IN In Pro*COBOL, SQLCA is declared as a status host variable. In Pro*FORTRAN, this status variable configuration is not supported.
-- OUT -- This status variable configuration is not supported.
-- OUT OUT SQLCA is declared as a status variable, and SQLSTATE is declared but is not recognized as a status variable.
-- OUT IN In Pro*COBOL, SQLCA is declared as a status host variable, and SQLSTATE is declared but is not recognized as a status variable. In Pro*FORTRAN, this status variable configuration is not supported.
-- IN -- SQLSTATE is declared as a status variable.
-- IN OUT SQLSTATE and SQLCA are declared as status variables.
-- IN IN In Pro*COBOL, SQLSTATE and SQLCA are declared as status host variables. In Pro*FORTRAN, this status variable configuration is not supported.
Table 8 - 3. Status Variable Behavior with ASSUME_SQLCODE=NO and MODE=ANSI|ANSI14



Declare Section (IN/OUT/ --)
SQLCODE SQLSTATE SQLCA
Behavior
OUT -- -- SQLCODE is declared and is presumed to be a status variable.
OUT -- OUT In Pro*COBOL, this status variable configuration is not supported. In Pro*FORTRAN, SQLCA is declared as a status variable, and SQLCODE is declared and is presumed to be a status variable.
OUT -- IN In Pro*COBOL, this status variable configuration is not supported. In Pro*FORTRAN, this status variable configuration is not supported.
OUT OUT -- SQLCODE is declared and is presumed to be a status variable, and SQLSTATE is declared but is not recognized as a status variable.
OUT OUT OUT In Pro*COBOL, this status variable configuration is not supported. In Pro*FORTRAN, SQLCA is declared as a status variable, SQLCODE is declared and is presumed to be a status variable, and SQLSTATE is declared but is not recognized as status variable.
OUT OUT IN In Pro*COBOL, this status variable configuration is not supported. In Pro*FORTRAN, this status variable configuration is not supported.
OUT IN -- SQLSTATE is declared as a status variable, and SQLCODE is declared and is presumed to be a status variable.
OUT IN OUT In Pro*COBOL, this status variable configuration is not supported. In Pro*FORTRAN, SQLSTATE and SQLCA are declared as status variables, and SQLCODE is declared and is presumed to be a status variable.
OUT IN IN In Pro*COBOL, this status variable configuration is not supported. In Pro*FORTRAN, this status variable configuration is not supported.
IN -- -- SQLCODE is declared as a status variable.
IN -- OUT In Pro*COBOL, this status variable configuration is not supported. In Pro*FORTRAN, SQLCODE and SQLCA are declared as a status variables.
IN -- IN In Pro*COBOL, this status variable configuration is not supported. In Pro*FORTRAN, this status variable configuration is not supported.
IN OUT -- SQLCODE is declared as a status variable, and SQLSTATE is declared but not as a status variable.
IN OUT OUT In Pro*COBOL, this status variable configuration is not supported. In Pro*FORTRAN, SQLCODE and SQLCA are declared as a status variables, and SQLSTATE is declared but is not recognized as a status variable.
IN OUT IN In Pro*COBOL, this status variable configuration is not supported. In Pro*FORTRAN, this status variable configuration is not supported.
IN IN -- SQLCODE and SQLSTATE are declared as a status variables.
IN IN OUT In Pro*COBOL, this status variable configuration is not supported. In Pro*FORTRAN, SQLCODE, SQLSTATE, and SQLCA are declared as a status variables.
IN IN IN In Pro*COBOL, this status variable configuration is not supported. In Pro*FORTRAN, this status variable configuration is not supported.
-- -- -- -- -- -- -- -- -- -- -- -- OUT OUT OUT IN IN IN -- OUT IN -- OUT IN -- OUT IN These status variable configurations are not supported. SQLCODE must be declared either inside or outside the Declare Section when ASSUME_SQLCODE=YES.
Table 8 - 4. Status Variable Behavior with ASSUME_SQLCODE=YES and MODE=ANSI|ANSI14



Status Variable Values

This section describes the values for the SQLCODE and SQLSTATE status variables. For information about the SQLCA status variable, see "Key Components of Error Reporting" [*].

SQLCODE Values

After every SQL operation, Oracle returns a status code to the SQLCODE variable currently in scope. The status code, which indicates the outcome of the SQL operation, can be any of the following numbers:

0

Oracle executed the SQL statement without detecting an error or exception.

> 0

Oracle executed the statement but detected an exception. This occurs when Oracle cannot find a row that meets the condition in your WHERE clause or when a SELECT INTO or FETCH returns no rows.

When MODE={ANSI|ANSI14|ANSI13}, +100 is returned to SQLCODE after an INSERT of no rows. This can happen when a subquery returns no rows to process.

< 0

Oracle did not execute the statement because of a database, system, network, or application error. Such errors can be fatal. When they occur, the current transaction should, in most cases, be rolled back. Negative return codes correspond to error codes listed in Oracle7 Server Messages.

You can learn the outcome of the most recent SQL operation by checking SQLCODE explicitly with your own code or implicitly with the WHENEVER statement.

When you declare SQLCODE instead of the SQLCA in a particular precompilation unit, the precompiler allocates an internal SQLCA for that unit. Your host program cannot access the internal SQLCA. If you declare the SQLCA and SQLCODE (Pro*FORTRAN only), Oracle returns the same status code to both after every SQL operation.

Note: When MODE={ORACLE|ANSI13}, declarations of SQLCODE are ignored.

SQLSTATE Values

SQLSTATE status codes consist of a two-character class code followed by a three-character subclass code. Aside from class code 00 (successful completion), the class code denotes a category of exceptions. Aside from subclass code 000 (not applicable), the subclass code denotes a specific exception within that category. For example, the SQLSTATE value `22012' consists of class code 22 (data exception) and subclass code 012 (division by zero).

Each of the five characters in a SQLSTATE value is a digit (0..9) or an uppercase Latin letter (A..Z). Class codes that begin with a digit in the range 0..4 or a letter in the range A..H are reserved for predefined conditions (those defined in SQL92). All other class codes are reserved for implementation-defined conditions. Within predefined classes, subclass codes that begin with a digit in the range 0..4 or a letter in the range A..H are reserved for predefined subconditions. All other subclass codes are reserved for implementation-defined subconditions. Figure 8 - 1 shows the coding scheme.

Figure 8 - 1. SQLSTATE Coding Scheme

Table 8 - 5 shows the classes predefined by SQL92.

Class Condition
00 successful completion
01 warning
02 no data
07 dynamic SQL error
08 connection exception
0A feature not supported
21 cardinality violation
22 data exception
23 integrity constraint violation
24 invalid cursor state
25 invalid transaction state
26 invalid SQL statement name
27 triggered data change violation
28 invalid authorization specification
2A direct SQL syntax error or access rule violation
2B dependent privilege descriptors still exist
2C invalid character set name
2D invalid transaction termination
2E invalid connection name
33 invalid SQL descriptor name
34 invalid cursor name
35 invalid condition number
37 dynamic SQL syntax error or access rule violation
3C ambiguous cursor name
3D invalid catalog name
3F invalid schema name
40 transaction rollback
42 syntax error or access rule violation
44 with check option violation
HZ remote database access
Table 8 - 5. Predefined Classes



Note: The class code HZ is reserved for conditions defined in International Standard ISO/IEC DIS 9579-2, Remote Database Access.

Table 8 - 6 shows how Oracle errors map to SQLSTATE status codes. In some cases, several Oracle errors map to the status code. In other cases, no Oracle error maps to the status code (so the last column is empty). Status codes in the range 60000 .. 99999 are implementation-defined.

Code Condition Oracle Error
00000 successful completion ORA-00000
01000 warning
01001 cursor operation conflict
01002 disconnect error
01003 null value eliminated in set function
01004 string data - right truncation
01005 insufficient item descriptor areas
01006 privilege not revoked
01007 privilege not granted
01008 implicit zero-bit padding
01009 search condition too long for info schema
0100A query expression too long for info schema
02000 no data ORA-01095 ORA-01403
07000 dynamic SQL error
07001 using clause does not match parameter specs
07002 using clause does not match target specs
07003 cursor specification cannot be executed
07004 using clause required for dynamic parameters
07005 prepared statement not a cursor specification
07006 restricted datatype attribute violation
07007 using clause required for result fields
07008 invalid descriptor count SQL-02126
07009 invalid descriptor index
08000 connection exception
08001 SQL client unable to establish SQL connection
08002 connection name in use
08003 connection does not exist SQL-02121
08004 SQL server rejected SQL connection
08006 connection failure
08007 transaction resolution unknown
0A000 feature not supported ORA-03000 .. 03099
0A001 multiple server transactions
21000 cardinality violation ORA-01427 SQL-02112
22000 data exception
22001 string data - right truncation ORA-01401 ORA-01406
22002 null value - no indicator parameter ORA-01405 SQL-02124
22003 numeric value out of range ORA-01426 ORA-01438 ORA-01455 ORA-01457
22005 error in assignment
22007 invalid datetime format
22008 datetime field overflow ORA-01800 .. 01899
22009 invalid time zone displacement value
22011 substring error
22012 division by zero ORA-01476
22015 interval field overflow
22018 invalid character value for cast
22019 invalid escape character ORA-00911 ORA-01425
22021 character not in repertoire
22022 indicator overflow ORA-01411
22023 invalid parameter value ORA-01025 ORA-01488 ORA-04000 .. 04019
22024 unterminated C string ORA-01479 .. 01480
22025 invalid escape sequence ORA-01424
22026 string data - length mismatch
22027 trim error
23000 integrity constraint violation ORA-00001 ORA-02290 .. 02299
24000 invalid cursor state ORA-01001 .. 01003 ORA-01410 ORA-08006 SQL-02114 SQL-02117 SQL-02118 SQL-02122
25000 invalid transaction state
26000 invalid SQL statement name
27000 triggered data change violation
28000 invalid authorization specification
2A000 direct SQL syntax error or access rule violation
2B000 dependent privilege descriptors still exist
2C000 invalid character set name
2D000 invalid transaction termination
2E000 invalid connection name
33000 invalid SQL descriptor name
34000 invalid cursor name
35000 invalid condition number
37000 dynamic SQL syntax error or access rule violation
3C000 ambiguous cursor name
3D000 invalid catalog name
3F000 invalid schema name
40000 transaction rollback ORA-02091 .. 02092
40001 serialization failure
40002 integrity constraint violation
40003 statement completion unknown
42000 syntax error or access rule violation ORA-00022 ORA-00251 ORA-00900 .. 00999 ORA-01031 ORA-01490 .. 01493 ORA-01700 .. 01799 ORA-01900 .. 02099 ORA-02140 .. 02289 ORA-02420 .. 02424 ORA-02450 .. 02499 ORA-03276 .. 03299 ORA-04040 .. 04059 ORA-04070 .. 04099
44000 with check option violation ORA-01402
60000 system errors ORA-00370 .. 00429 ORA-00600 .. 00899 ORA-06430 .. 06449 ORA-07200 .. 07999 ORA-09700 .. 09999
61000 resource error ORA-00018 .. 00035 ORA-00050 .. 00068 ORA-02376 .. 02399 ORA-04020 .. 04039
62000 multi-threaded server and detached process errors ORA-00100 .. 00120 ORA-00440 .. 00569
63000 Oracle*XA and two-task interface errors ORA-00150 .. 00159 SQL-02128 ORA-02700 .. 02899 ORA-03100 .. 03199 ORA-06200 .. 06249 SQL-02128
64000 control file, database file, and redo file errors; archival and media recovery errors ORA-00200 .. 00369 ORA-01100 .. 01250
65000 PL/SQL errors ORA-06500 .. 06599
66000 SQL*Net driver errors ORA-06000 .. 06149 ORA-06250 .. 06429 ORA-06600 .. 06999 ORA-12100 .. 12299 ORA-12500 .. 12599
67000 licensing errors ORA-00430 .. 00439
69000 SQL*Connect errors ORA-00570 .. 00599 ORA-07000 .. 07199
72000 SQL execute phase errors ORA-01000 .. 01099 ORA-01400 .. 01489 ORA-01495 .. 01499 ORA-01500 .. 01699 ORA-02400 .. 02419 ORA-02425 .. 02449 ORA-04060 .. 04069 ORA-08000 .. 08190 ORA-12000 .. 12019 ORA-12300 .. 12499 ORA-12700 .. 21999
82100 out of memory (could not allocate) SQL-02100
82101 inconsistent cursor cache: unit cursor/global cursor mismatch SQL-02101
82102 inconsistent cursor cache: no global cursor entry SQL-02102
82103 inconsistent cursor cache: out of range cursor cache reference SQL-02103
82104 inconsistent host cache: no cursor cache available SQL-02104
82105 inconsistent cursor cache: global cursor not found SQL-02105
82106 inconsistent cursor cache: invalid Oracle cursor number SQL-02106
82107 program too old for runtime library SQL-02107
82108 invalid descriptor passed to runtime library SQL-02108
82109 inconsistent host cache: host reference is out of range SQL-02109
82110 inconsistent host cache: invalid host cache entry type SQL-02110
82111 heap consistency error SQL-02111
82112 unable to open message file SQL-02113
82113 code generation internal consistency failed SQL-02115
82114 reentrant code generator gave invalid context SQL-02116
82115 invalid hstdef argument SQL-02119
82116 first and second arguments to sqlrcn both null SQL-02120
82117 invalid OPEN or PREPARE for this connection SQL-02122
82118 application context not found SQL-02123
82119 connect error; can't get error text SQL-02125
82120 precompiler/SQLLIB version mismatch. SQL-02127
82121 FETCHed number of bytes is odd SQL-02129
82122 EXEC TOOLS interface is not available SQL-02130
82123 runtime context in use SQL-02131
82124 unable to allocate runtime context SQL-02131
82125 unable to initialize process for use with threads SQL-02133
82126 invalid runtime context SQL-02134
90000 debug events ORA-10000 .. 10999
99999 catch all all others
HZ000 remote database access
Table 8 - 6. SQLSTATE Codes



Using the SQL Communications Area

The SQL Communications area (SQLCA) is a record-like data structure. Its fields contain error, warning, and status information updated by Oracle whenever a SQL statement is executed. Thus, the SQLCA always reflects the outcome of the most recent SQL operation. To determine the outcome, you can check variables in the SQLCA.

In host languages that allow both local and global declarations, your program can have more than one SQLCA. For example, it might have one global SQLCA and several local ones. Access to a local SQLCA is limited by its scope within the program. Oracle returns information only to the "active" SQLCA.

Note: When your application uses SQL*Net to access a combination of local and remote databases concurrently, all the databases write to one SQLCA. There is not a different SQLCA for each database. For more information, see "Concurrent Logons" [*].

When MODE={ORACLE|ANSI13}, the SQLCA is required; if the SQLCA is not declared, compile-time errors will occur. The SQLCA is optional when MODE={ANSI|ANSI14}, but you cannot use the WHENEVER SQLWARNING statement without declaring SQLCA. So, if you want to use the WHENEVER SQLWARNING statement, you must declare the SQLCA.

Note: If you declare SQLCODE instead of the SQLCA in a particular compilation unit, the precompiler allocates an internal SQLCA for that unit. Your host program cannot access the internal SQLCA. If you declare the SQLCA and SQLCODE (Pro*FORTRAN only), Oracle returns the same status code to both after every SQL operation.

When MODE={ANSI|ANSI14}, you must declare either SQLSTATE (see "Declaring SQLSTATE" [*]) or SQLCODE (see "Declaring SQLCODE" [*]) or both. The SQLSTATE status variable supports the SQLSTATE status variable specified by the SQL92 standard. You can use the SQLSTATE status variable with or without SQLCODE. See Table 8 - 3 and Table 8 - 4 for more information.

Declaring the SQLCA

To declare the SQLCA, simply include it (using an EXEC SQL INCLUDE statement) in your host-language source file as follows:

*     Include the Oracle Communications Area (ORACA). 
      EXEC SQL INCLUDE ORACA
EXEC SQL INCLUDE SQLCA; 

The SQLCA is used if and only if there is an INCLUDE of the SQLCA.

When you precompile your program, the INCLUDE SQLCA statement is replaced by several variable declarations that allow Oracle to communicate with the program.

Declaring the SQLCA in Pro*COBOL

In Pro*COBOL, it makes no difference whether the INCLUDE is inside or outside of a Declare Section. For more information about declaring the SQLCA in Pro*COBOL, see the Pro*COBOL Supplement to the Oracle Precompilers Guide.

Declaring the SQLCA in Pro*FORTRAN

In Pro*FORTRAN, the SQLCA must be declared outside the Declare Section, because it is a COMMON block. Furthermore, the SQLCA must come before the CONNECT statement and the first executable FORTRAN statement.

You must declare the SQLCA in each subroutine and function that contains SQL statements. Every time a SQL statement in one of the subroutines or functions is executed, Oracle updates the SQLCA held in the COMMON block.

Ordinarily, only the order and datatypes of variables in a COMMON-list matter, not their names. However, you cannot rename the SQLCA variables because the precompiler generates code that refers to them. Thus, all declarations of the SQLCA must be identical. For more information about declaring the SQLCA in Pro*FORTRAN, see the Pro*FORTRAN Supplement to the Oracle Precompilers Guide.

What's in the SQLCA?

The SQLCA contains the following runtime information about the outcome of SQL statements:

Figure 8 - 2 shows all the variables in the SQLCA. To see the SQLCA structure and variable names in a particular host language, refer to your supplement to this Guide.

Figure 8 - 2. SQLCA Variables

Key Components of Error Reporting

Error reporting depends on variables in the SQLCA. This section highlights the key components of error reporting. The next section takes a close look at the SQLCA.

Status Codes

Every executable SQL statement returns a status code to the SQLCA variable SQLCODE, which you can check implicitly with the WHENEVER statement or explicitly with your own code.

Status codes can be zero, less than zero, or greater than zero. See "SQLCODE" [*] for complete SQLCODE descriptions.

Warning Flags

Warning flags are returned in the SQLCA variables SQLWARN(0) through SQLWARN(7), which you can check implicitly or explicitly. These warning flags are useful for runtime conditions not considered errors by Oracle. For example, when DBMS=V6, if an indicator variable is available, Oracle signals a warning after assigning a truncated column value to a host variable. (If no indicator variable is available, Oracle issues an error message.)

Rows-Processed Count

The number of rows processed by the most recently executed SQL statement is returned in the SQLCA variable SQLERRD(3), which you can check explicitly.

Speaking strictly, this variable is not for error reporting, but it can help you avoid mistakes. For example, suppose you expect to delete about ten rows from a table. After the deletion, you check SQLERRD(3) and find that 75 rows were processed. To be safe, you might want to roll back the deletion and examine the search condition in your WHERE clause.

Parse Error Offset

Before executing a SQL statement, Oracle must parse it, that is, examine it to make sure it follows syntax rules and refers to valid database objects. If Oracle finds an error, an offset is stored in the SQLCA variable SQLERRD(5), which you can check explicitly. The offset specifies the character position in the SQL statement at which the parse error begins. The first character occupies position zero. For example, if the offset is 9, the parse error begins at the tenth character.

By default, static SQL statements are checked for syntactic errors at precompile time. So, SQLERRD(5) is most useful for debugging dynamic SQL statements, which your program accepts or builds at run time.

Parse errors arise from missing, misplaced, or misspelled keywords, invalid options, nonexistent tables, and the like. For example, the dynamic SQL statement

UPDATE EMP SET JIB = :job_title WHERE EMPNO = :emp_number

causes the parse error

ORA-00904: invalid column name

because the column name JOB is misspelled. The value of SQLERRD(5) is 15 because the erroneous column name JIB begins at the sixteenth character.

If your SQL statement does not cause a parse error, Oracle sets SQLERRD(5) to zero. Oracle also sets SQLERRD(5) to zero if a parse error begins at the first character (which occupies position zero). So, check SQLERRD(5) only if SQLCODE is negative, which means that an error has occurred.

Error Message Text

The error code and message for Oracle errors are available in the SQLCA variable SQLERRMC. At most, the first 70 characters of text are stored. To get the full text of messages longer than 70 characters, you use the SQLGLM function. See "Getting the Full Text of Error Messages" [*].

SQLCA Structure

This section describes the structure of the SQLCA, its fields, and the values they can store.

SQLCAID

This string field is initialized to "SQLCA" to identify the SQL Communications Area.

SQLCABC

This integer field holds the length, in bytes, of the SQLCA structure.

SQLCODE

This integer field holds the status code of the most recently executed SQL statement. The status code, which indicates the outcome of the SQL operation, can be any of the following numbers:

0

Oracle executed the statement without detecting an error or exception.

> 0

Oracle executed the statement but detected an exception. This occurs when Oracle cannot find a row that meets your WHERE-clause search condition or when a SELECT INTO or FETCH returns no rows.

< 0

When MODE={ANSI|ANSI14|ANSI13}, +100 is returned to SQLCODE after an INSERT of no rows. This can happen when a subquery returns no rows to process.

Oracle did not execute the statement because of a database, system, network, or application error. Such errors can be fatal. When they occur, the current transaction should, in most cases, be rolled back.

Negative return codes correspond to error codes listed in Oracle7 Server Messages.

SQLERRM

This subrecord contains the following two fields:

SQLERRML

This integer field holds the length of the message text stored in SQLERRMC.

SQLERRMC

This string field holds the message text for the error code stored in SQLCODE and can store up to 70 characters. For the full text of messages longer than 70 characters, use the SQLGLM function.

Verify SQLCODE is negative

before you reference SQLERRMC. If you reference SQLERRMC when SQLCODE is zero, you get the message text associated with a prior SQL statement.

SQLERRP

This string field is reserved for future use.

SQLERRD

This array of binary integers has six elements. Descriptions of the fields in SQLERRD (called SQLERD in FORTRAN) follow:

SQLERRD(1)

This field is reserved for future use.

SQLERRD(2)

This field is reserved for future use.

SQLERRD(3)

This field holds the number of rows processed by the most recently executed SQL statement. However, if the SQL statement failed, the value of SQLERRD(3) is undefined, with one exception. If the error occurred during an array operation, processing stops at the row that caused the error, so SQLERRD(3) gives the number of rows processed successfully.

The rows-processed count is zeroed after an OPEN statement and incremented after a FETCH statement. For the EXECUTE, INSERT, UPDATE, DELETE, and SELECT INTO statements, the count reflects the number of rows processed successfully. The count does

not include rows processed by an update or delete cascade. For example, if 20 rows are deleted because they meet WHERE-clause criteria, and 5 more rows are deleted because they now (after the primary delete) violate column constraints, the count is 20 not 25.

SQLERRD(4)

This field is reserved for future use.

SQLERRD(5)

This field holds an offset that specifies the character position at which a parse error begins in the most recently executed SQL statement. The first character occupies position zero.

SQLERRD(6)

This field is reserved for future use.

SQLWARN

This array of single characters has eight elements. They are used as warning flags. Oracle sets a flag by assigning it a "W" (for warning) character value. The flags warn of exceptional conditions.

For example, a warning flag is set when Oracle assigns a truncated column value to an output host variable.

Note: While Figure 8 - 2 illustrates SQLWARN as an array, it is implemented in Pro*COBOL as a group item with elementary PIC X items named SQLWARN0 through SQLWARN7. The Pro*FORTRAN implementation is composed of the LOGICAL variables, SQLWN0 through SQLWN7.

Descriptions of the fields in SQLWARN follow:

SQLWARN(0)

This flag is set if another warning flag is set.

SQLWARN(1)

This flag is set if a truncated column value was assigned to an output host variable. This applies only to character data. Oracle truncates certain numeric data without setting a warning or returning a negative SQLCODE value.

To find out if a column value was truncated and by how much, check the indicator variable associated with the output host variable. The (positive) integer returned by an indicator variable is the original length of the column value. You can increase the length of the host variable accordingly.

SQLWARN(2)

This flag is set if one or more nulls were ignored in the evaluation of a SQL group function such as AVG, COUNT, or MAX. This behavior is expected because, except for COUNT(*), all group functions ignore nulls. If necessary, you can use the SQL function NVL to temporarily assign values (zeros, for example) to the null column entries.

SQLWARN(3)

This flag is set if the number of columns in a query select list does not equal the number of host variables in the INTO clause of the SELECT or FETCH statement. The number of items returned is the lesser of the two.

SQLWARN(4)

This flag is set if every row in a table was processed by an UPDATE or DELETE statement without a WHERE clause. An update or deletion is called unconditional if no search condition restricts the number of rows processed. Such updates and deletions are unusual, so Oracle sets this warning flag. That way, you can roll back the transaction if necessary

SQLWARN(5)

This flag is set when an EXEC SQL CREATE {PROCEDURE|FUNCTION|PACKAGE|PACKAGE BODY} statement fails because of a PL/SQL compilation error.

SQLWARN(6)

This flag is no longer in use.

SQLWARN(7)

This flag is no longer in use.

SQLEXT

This string field is reserved for future use.

PL/SQL Considerations

When your precompiler program executes an embedded PL/SQL block, not all fields in the SQLCA are set. For example, if the block fetches several rows, the rows-processed count, SQLERRD(3), is set to 1, not the actual number of rows fetched. So, you should rely only on the SQLCODE and SQLERRM fields in the SQLCA after executing a PL/SQL block.

Getting the Full Text of Error Messages

The SQLCA can accommodate error messages up to 70 characters long. To get the full text of longer (or nested) error messages, you need the SQLGLM function. If connected to Oracle, you can call SQLGLM using the syntax

SQLGLM(message_buffer, buffer_size, message_length); 

where:

message_buffer

is the text buffer in which you want Oracle to store the error message (Oracle blank-pads to the end of this buffer).

buffer_size

is an integer variable that specifies the maximum size of the buffer in bytes.

message_length

is an integer variable in which Oracle stores the actual length of the error message.

The maximum length of an Oracle error message is 512 characters including the error code, nested messages, and message inserts such as table and column names. The maximum length of an error message returned by SQLGLM depends on the value you specify for buffer_size.

In the following example, you call SQLGLM to get an error message of up to 100 characters in length:

-- declare variables for function call 
msg_buffer   CHARACTER(100); 
buf_size     INTEGER; 
msg_length   INTEGER; 
set buf_size = 100; 
EXEC SQL WHENEVER SQLERROR DO sql_error; 
-- other statements 
ROUTINE sql_error
BEGIN
    -- get full text of error message 
    SQLGLM(msg_buffer, buf_size, msg_length); 
    display contents of msg_buffer; 
    exit program with an error 
END sql_error;

Notice that SQLGLM is called only when a SQL error has occurred. Always make sure SQLCODE is negative before calling SQLGLM. If you call SQLGLM when SQLCODE is zero, you get the message text associated with a prior SQL statement.

Using the WHENEVER Statement

By default, precompiled programs ignore Oracle error and warning conditions and continue processing if possible. To perform automatic condition checking and error handling, use the WHENEVER statement.

With the WHENEVER statement you can specify actions to be taken when Oracle detects an error, warning condition, or "not found" condition. These actions include continuing with the next statement, calling a routine, branching to a labeled statement, or stopping.

You code the WHENEVER statement using the following syntax:

EXEC SQL WHENEVER <condition> <action>; 

You can have Oracle automatically check the SQLCA for any of the following conditions.

SQLWARNING

SQLWARN(0) is set because Oracle returned a warning (one of the warning flags, SQLWARN(1) through SQLWARN(7), is also set) or SQLCODE has a positive value other than +1403. For example, SQLWARN(1) is set when Oracle assigns a truncated column value to an output host variable.

Declaring the SQLCA is optional when MODE={ANSI|ANSI14}. To use WHENEVER SQLWARNING, however, you must declare the SQLCA.

SQLERROR

SQLCODE has a negative value because Oracle returned an error.

NOT FOUND

SQLCODE has a value of +1403 (+100 when MODE={ANSI|ANSI14| ANSI13}), because Oracle could not find a row that meets the search condition of a WHERE clause, or a SELECT INTO or FETCH returned no rows. When MODE={ANSI|ANSI14|ANSI13}, +100 is returned to SQLCODE after an INSERT of no rows.

When Oracle detects one of the preceding conditions, you can have your program take any of the following actions.

CONTINUE

Your program continues to run with the next statement if possible. This is the default action, equivalent to not using the WHENEVER statement. You can use it to "turn off" condition checking.

DO

Your program transfers control to an internal routine. When the end of the routine is reached, control transfers to the statement that follows the failed SQL statement.

A routine is any functional program unit that can be invoked such as a COBOL paragraph or FORTRAN subroutine. In this context, separately compiled programs, such as COBOL subroutines, are not routines.

The usual rules for entering and exiting a routine apply. However, passing parameters to the routine is not allowed. Furthermore, the routine must not return a value.

The parameter routine_call is a host language invocation, as in

EXEC SQL                                                -- COBOL
    WHENEVER <condition> DO PERFORM <paragraph_name>    -- COBOL
END-EXEC.                                               -- COBOL

or

EXEC SQL                                                -- FORTRAN
    WHENEVER <condition> DO CALL <subroutine_name>      -- FORTRAN

GOTO

Your program branches to a labeled statement.

STOP

Your program stops running and uncommitted work is rolled back.

Be careful. The STOP action displays no messages before logging off Oracle. In Pascal, the STOP action is illegal because Pascal has no equivalent command.

Some Examples

If you want your program to

simply code the following WHENEVER statements before the first executable SQL statement:

EXEC SQL WHENEVER NOT FOUND GOTO close_cursor; 
EXEC SQL WHENEVER SQLWARNING CONTINUE; 
EXEC SQL WHENEVER SQLERROR GOTO error_handler; 

The following Pro*C example uses WHENEVER...DO statements to handle specific errors:

EXEC SQL WHENEVER SQLERROR DO handle_insert_error; 
EXEC SQL INSERT INTO EMP (EMPNO, ENAME, DEPTNO) 
   VALUES (:emp_number, :emp_name, :dept_number); 
EXEC SQL WHENEVER SQLERROR DO handle_delete_error; 
EXEC SQL DELETE FROM DEPT WHERE DEPTNO = :dept_number; 
... 
ROUTINE handle_insert_error; 
    BEGIN 
        IF sqlca.sqlcode = -1 THEN          -- duplicate key value 
            ... 
        ELSEIF sqlca.sqlcode = -1401 THEN   -- value too large 
            ... 
        ENDIF; 
        ... 
    END; 
ROUTINE handle_delete_error; 
    BEGIN 
        IF sqlca.sqlerrd(3) = 0 THEN        -- no rows deleted 
            ... 
        ELSE 
            ... 
        ENDIF; 
        ... 
    END; 
... 

Notice how the procedures check variables in the SQLCA to determine a course of action.

Scope

Because WHENEVER is a declarative statement, its scope is positional, not logical. It tests all executable SQL statements that follow it in the source file, not in the flow of program logic. So, code the WHENEVER statement before the first executable SQL statement you want to test.

A WHENEVER statement stays in effect until superseded by another WHENEVER statement checking for the same condition.

In the example below, the first WHENEVER SQLERROR statement is superseded by a second, and so applies only to the CONNECT statement. The second WHENEVER SQLERROR statement applies to both the UPDATE and DROP statements, despite the flow of control from step1 to step3.

step1: 
EXEC SQL WHENEVER SQLERROR STOP; 
EXEC SQL CONNECT :username IDENTIFIED BY :password; 
    ... 
    GOTO step3; 
step2: 
EXEC SQL WHENEVER SQLERROR CONTINUE; 
EXEC SQL UPDATE EMP SET SAL = SAL * 1.10; 
    ... 
step3: 
    EXEC SQL DROP INDEX EMP_INDEX; 
    ... 

Guidelines

The following guidelines will help you avoid some common pitfalls.

Placing the Statements. In general, code a WHENEVER statement before the first executable SQL statement in your program. This ensures that all ensuing errors are trapped because WHENEVER statements stay in effect to the end of a file.

Handling End-of-Data Conditions. Your program should be prepared to handle an end-of-data condition when using a cursor to fetch rows. If a FETCH returns no data, the program should branch to a labeled section of code where a CLOSE command is issued, as follows:

SQL WHENEVER NOT FOUND GOTO no_more; 
... 
no_more: 
    ... 
    EXEC SQL CLOSE my_cursor; 
    ... 

Avoiding Infinite Loops. If a WHENEVER SQLERROR GOTO statement branches to an error handling routine that includes an executable SQL statement, your program might enter an infinite loop if the SQL statement fails with an error. You can avoid this by coding WHENEVER SQLERROR CONTINUE before the SQL statement, as shown in the following example:

EXEC SQL WHENEVER SQLERROR GOTO sql_error; 
... 
sql_error: 
    EXEC SQL WHENEVER SQLERROR CONTINUE; 
    EXEC SQL ROLLBACK WORK RELEASE; 
    ... 

Without the WHENEVER SQLERROR CONTINUE statement, a ROLLBACK error would invoke the routine again, starting an infinite loop.

Careless use of WHENEVER can cause problems. For example, the following code enters an infinite loop if the DELETE statement sets NOT FOUND because no rows meet the search condition:

-- improper use of WHENEVER 
... 
EXEC SQL WHENEVER NOT FOUND GOTO no_more; 
LOOP 
    EXEC SQL FETCH emp_cursor INTO :emp_name, :salary; 
    ... 
ENDLOOP; 
no_more: 
    EXEC SQL DELETE FROM EMP WHERE EMPNO = :emp_number; 
    ... 

In the next example, you handle the NOT FOUND condition properly by resetting the GOTO target:

-- proper use of WHENEVER 
... 
EXEC SQL WHENEVER NOT FOUND GOTO no_more; 
LOOP 
    EXEC SQL FETCH emp_cursor INTO :emp_name, :salary; 
    ... 
ENDLOOP; 
no_more: 
    EXEC SQL WHENEVER NOT FOUND GOTO no_match; 
    EXEC SQL DELETE FROM EMP WHERE EMPNO = :emp_number; 
    ... 
no_match: 
    ... 

Maintaining Addressability. With host languages that allow local as well as global identifiers, make sure all SQL statements governed by a WHENEVER GOTO statement can branch to the GOTO label. The following code results in a compile-time error because labelA in FUNC1 is not within the scope of the INSERT statement in FUNC2:

FUNC1 
    BEGIN 
         EXEC SQL WHENEVER SQLERROR GOTO labelA; 
         EXEC SQL DELETE FROM EMP WHERE DEPTNO = :dept_number; 
        ... 
        labelA: 
        ... 
   END; 
FUNC2 
   BEGIN 
        EXEC SQL INSERT INTO EMP (JOB) VALUES (:job_title); 
       ... 
   END; 

The label to which a WHENEVER GOTO statement branches must be in the same precompilation file as the statement.

Returning after an Error. If your program must return after handling an error, use the DO routine_call action. Alternatively, you can test the value of SQLCODE, as shown in the following example:

EXEC SQL UPDATE EMP SET SAL = SAL * 1.10; 
IF sqlca.sqlcode < 0 THEN 
    -- handle error 
EXEC SQL DROP INDEX EMP_INDEX; 
... 

Just make sure no WHENEVER GOTO or WHENEVER STOP statement is active.

Getting the Text of SQL Statements

In many precompiler applications, it is convenient to know the text of the statement being processed, its length, and the SQL command (such as INSERT or SELECT) that it contains. This is especially true for applications that use dynamic SQL.

The routine SQLGLS, which is part of the SQLLIB runtime library, returns the following information:

You can call SQLGLS after issuing a static SQL statement. With dynamic SQL Method 1, you can call SQLGLS after the SQL statement is executed. With dynamic SQL Method 2, 3, or 4, you can call SQLGLS after the statement is prepared.

To call SQLGLS, you use the following syntax:

SQLGLS(SQLSTM, STMLEN, SQLFC) 

Table 8 - 7 shows the host-language datatypes available for the parameters in the SQLGLS argument list.

Parameter Language Datatype
SQLSTM COBOL PIC X(n)
FORTRAN CHARACTER*n
STMLEN, SQLFC COBOL PIC S9(9) COMP
FORTRAN INTEGER*4
Table 8 - 7. Parameter Datatypes



All parameters must be passed by reference. This is usually the default parameter passing convention; you need not take special action.

The parameter SQLSTM is a blank-padded (not null-terminated) character buffer that holds the returned text of the SQL statement. Your program must statically declare the buffer or dynamically allocate memory for it.

The length parameter STMLEN is a four-byte integer. Before calling SQLGLS, set this parameter to the actual size (in bytes) of the SQLSTM buffer. When SQLGLS returns, the SQLSTM buffer contains the SQL statement text blank padded to the length of the buffer. STMLEN returns the actual number of bytes in the returned statement text, not counting the blank padding. However, STMLEN returns a zero if an error occurred.

Some possible errors follow:

The parameter SQLFC is a four-byte integer that returns the SQL function code for the SQL command in the statement. Table 8 - 8 shows the function code for each SQL command.

SQLGLS does not return statements that contain the following commands:

There are no SQL function codes for these statements.

Code SQL Function Code SQL Function
01 CREATE TABLE 39 AUDIT
02 SET ROLE 40 NOAUDIT
03 INSERT 41 ALTER INDEX
04 SELECT 42 CREATE EXTERNAL DATABASE
05 UPDATE 43 DROP EXTERNAL DATABASE
06 DROP ROLE 44 CREATE DATABASE
07 DROP VIEW 45 ALTER DATABASE
08 DROP TABLE 46 CREATE ROLLBACK SEGMENT
09 DELETE 47 ALTER ROLLBACK SEGMENT
10 CREATE VIEW 48 DROP ROLLBACK SEGMENT
11 DROP USER 49 CREATE TABLESPACE
12 CREATE ROLE 50 ALTER TABLESPACE
13 CREATE SEQUENCE 51 DROP TABLESPACE
14 ALTER SEQUENCE 52 ALTER SESSION
15 (not used) 53 ALTER USER
16 DROP SEQUENCE 54 COMMIT
17 CREATE SCHEMA 55 ROLLBACK
18 CREATE CLUSTER 56 SAVEPOINT
19 CREATE USER 57 CREATE CONTROL FILE
20 CREATE INDEX 58 ALTER TRACING
21 DROP INDEX 59 CREATE TRIGGER
22 DROP CLUSTER 60 ALTER TRIGGER
23 VALIDATE INDEX 61 DROP TRIGGER
24 CREATE PROCEDURE 62 ANALYZE TABLE
25 ALTER PROCEDURE 63 ANALYZE INDEX
26 ALTER TABLE 64 ANALYZE CLUSTER
27 EXPLAIN 65 CREATE PROFILE
28 GRANT 66 DROP PROFILE
29 REVOKE 67 ALTER PROFILE
30 CREATE SYNONYM 68 DROP PROCEDURE
31 DROP SYNONYM 69 (not used)
32 ALTER SYSTEM SWITCH LOG 70 ALTER RESOURCE COST
33 SET TRANSACTION 71 CREATE SNAPSHOT LOG
34 PL/SQL EXECUTE 72 ALTER SNAPSHOT LOG
35 LOCK TABLE 73 DROP SNAPSHOT LOG
36 (not used) 74 CREATE SNAPSHOT
37 RENAME 75 ALTER SNAPSHOT
38 COMMENT 76 DROP SNAPSHOT
Table 8 - 8. SQL Codes



Using the Oracle Communications Area

In the same way the SQLCA handles standard SQL communications; the Oracle Communications Area (ORACA) handles Oracle communications. When you need more information about runtime errors and status changes than the SQLCA provides, use the ORACA. It contains an extended set of diagnostic tools. However, use of the ORACA is optional because it adds to runtime overhead.

Besides helping you to diagnose problems, the ORACA lets you monitor your program's use of Oracle resources such as the SQL Statement Executor and the cursor cache.

In host languages that allow local as well as global declarations, your program can have more than one ORACA. For example, it might have one global ORACA and several local ones. Access to a local ORACA is limited by its scope within the program. Oracle returns information only to the "active" ORACA. The information is available only after a commit or rollback.

Declaring the ORACA

To declare the ORACA, simply include it (using an EXEC SQL INCLUDE statement) in your host-language source file as follows:

*     Include the Oracle Communications Area (ORACA). 
      EXEC SQL INCLUDE ORACA

The ORACA must be declared outside the Declare Section.

When you precompile your program, the INCLUDE ORACA statement is replaced by several program variable declarations. These declarations allow Oracle to communicate with your program.

Enabling the ORACA

To enable the ORACA, you must specify the ORACA option, either on the command line with

ORACA=YES 

or inline with

EXEC ORACLE OPTION (ORACA=YES); 

Then, you must choose appropriate runtime options by setting flags in the ORACA.

What's in the ORACA?

The ORACA contains option settings, system statistics, and extended diagnostics such as

Figure 8 - 3 shows all the variables in the ORACA. To see the ORACA structure and variable names in a particular host language, refer to your supplement to this Guide.

Figure 8 - 3. ORACA Variables

Choosing Runtime Options

The ORACA includes several option flags. Setting these flags by assigning them non-zero values allows you to

The descriptions below will help you choose the options you need.

ORACA Structure

This section describes the structure of the ORACA, its fields, and the values they can store.

ORACAID

This string field is initialized to "ORACA" to identify the Oracle Communications Area.

ORACABC

This integer field holds the length, expressed in bytes, of the ORACA data structure.

ORACCHF

If the master DEBUG flag (ORADBGF) is set, this flag lets you check the cursor cache for consistency before every cursor operation.

The Oracle runtime library does the consistency checking and might issue error messages, which are listed in Oracle7 Server Messages. They are returned to the SQLCA just like Oracle error messages.

This flag has the following settings:

0

Disable cache consistency checking (the default).

1

Enable cache consistency checking.

ORADBGF

This master flag lets you choose all the DEBUG options. It has the following settings:

0

Disable all DEBUG operations (the default).

1

Enable all DEBUG operations.

ORAHCHF

If the master DEBUG flag (ORADBGF) is set, this flag tells the Oracle runtime library to check the heap for consistency every time the precompiler dynamically allocates or frees memory. This is useful for detecting program bugs that upset memory.

This flag must be set before the CONNECT command is issued and, once set, cannot be cleared; subsequent change requests are ignored. It has the following settings:

0

Disable heap consistency checking (the default).

1

Enable heap consistency checking.

ORASTXTF

This flag lets you specify when the text of the current SQL statement is saved. It has the following settings:

0

Never save the SQL statement text (the default).

1

Save the SQL statement text on SQLERROR only.

2

Save the SQL statement text on SQLERROR or SQLWARNING.

3

Always save the SQL statement text.

The SQL statement text is saved in the ORACA subrecord named ORASTXT.

Diagnostics

The ORACA provides an enhanced set of diagnostics; the following variables help you to locate errors quickly.

ORASTXT

This subrecord helps you find faulty SQL statements. It lets you save the text of the last SQL statement parsed by Oracle. It contains the following two fields:

ORASTXTL

This integer field holds the length of the current SQL statement.

ORASTXTC

This string field holds the text of the current SQL statement. At most, the first 70 characters of text are saved.

Statements parsed by the precompiler, such as CONNECT, FETCH, and COMMIT, are not saved in the ORACA.

ORASFNM

This subrecord identifies the file containing the current SQL statement and so helps you find errors when multiple files are precompiled for one application. It contains the following two fields:

ORASFNML

This integer field holds the length of the filename stored in ORASFNMC.

ORASFNMC

This string field holds the filename. At most, the first 70 characters are stored.

ORASLNR

This integer field identifies the line at (or near) which the current SQL statement can be found.

Cursor Cache Statistics

The variables below let you gather cursor cache statistics. They are automatically set by every COMMIt or ROLLBACK statement your program issues. Internally, there is a set of these variables for each CONNECTed database. The current values in the ORACA pertain to the database against which the last commit or rollback was executed.

ORAHOC

This integer field records the highest value to which MAXOPENCURSORS was set during program execution.

ORAMOC

This integer field records the maximum number of open Oracle cursors required by your program. This number can be higher than ORAHOC if MAXOPENCURSORS was set too low, which forced the precompiler to extend the cursor cache.

ORACOC

This integer field records the current number of open Oracle cursors required by your program.

ORANOR

This integer field records the number of cursor cache reassignments required by your program. This number shows the degree of "thrashing" in the cursor cache and should be kept as low as possible.

ORANPR

This integer field records the number of SQL statement parses required by your program.

ORANEX

This integer field records the number of SQL statement executions required by your program. The ratio of this number to the ORANPR number should be kept as high as possible. In other words, avoid unnecessary reparsing. For help, see Appendix C.

An Example

The following program prompts for a department number, inserts the name and salary of each employee in that department into one of two tables, then displays diagnostic information from the ORACA:

EXEC SQL BEGIN DECLARE SECTION; 
    username     CHARACTER(20); 
    password     CHARACTER(20); 
    emp_name     INTEGER; 
    dept_number  INTEGER; 
    salary       REAL; 
EXEC SQL END DECLARE SECTION; 
EXEC SQL INCLUDE SQLCA; 
EXEC SQL INCLUDE ORACA; 
display 'Username? '; 
read username; 
display 'Password? '; 
read password; 
EXEC SQL WHENEVER SQLERROR DO sql_error; 
EXEC SQL CONNECT :username IDENTIFIED BY :password; 
display 'Connected to Oracle'; 
EXEC ORACLE OPTION (ORACA=YES); 
-- set flags in the ORACA 
set oraca.oradbgf  = 1;  -- enable debug operations 
set oraca.oracchf  = 1;  -- enable cursor cache consistency check
set oraca.orastxtf = 3;  -- always save the SQL statement 
display 'Department number? '; 
read dept_number; 
EXEC SQL DECLARE emp_cursor CURSOR FOR 
    SELECT ENAME, SAL + NVL(COMM,0) 
    FROM EMP 
    WHERE DEPTNO = :dept_number; 
EXEC SQL OPEN emp_cursor; 
EXEC SQL WHENEVER NOT FOUND DO no_more; 
rLOOP 
    EXEC SQL FETCH emp_cursor INTO :emp_name, :salary; 
    IF salary < 2500 THEN 
        EXEC SQL INSERT INTO PAY1 VALUES (:emp_name, :salary); 
    ELSE 
        EXEC SQL INSERT INTO PAY2 VALUES (:emp_name, :salary); 
    ENDIF; 
ENDLOOP; 
ROUTINE no_more
BEGIN
    EXEC SQL CLOSE emp_cursor; 
    EXEC SQL WHENEVER SQLERROR CONTINUE; 
    EXEC SQL COMMIT WORK RELEASE; 
    display 'Last SQL statement: ', oraca.orastxt.orastxtc; 
    display '... at or near line number:  ', oraca.oraslnr; 
    display 
    display '          Cursor Cache Statistics'; 
    display '-------------------------------------------'; 
    display 'Maximum value of MAXOPENCURSORS     ', oraca.orahoc; 
    display 'Maximum open cursors required:      ', oraca.oramoc; 
    display 'Current number of open cursors:     ', oraca.oracoc; 
    display 'Number of cache reassignments:      ', oraca.oranor; 
    display 'Number of SQL statement parses:     ', oraca.oranpr; 
    display 'Number of SQL statement executions: ', oraca.oranex; 
    exit program; 
END no_more;
ROUTINE sql_error
BEGIN
    EXEC SQL WHENEVER SQLERROR CONTINUE; 
    EXEC SQL ROLLBACK WORK RELEASE; 
    display 'Last SQL statement: ', oraca.orastxt.orastxtc; 
    display '... at or near line number:  ', oraca.oraslnr; 
    display 
    display '          Cursor Cache Statistics'; 
    display '-------------------------------------------'; 
    display 'Maximum value of MAXOPENCURSORS     ', oraca.orahoc; 
    display 'Maximum open cursors required:      ', oraca.oramoc; 
    display 'Current number of open cursors:     ', oraca.oracoc; 
    display 'Number of cache reassignments:      ', oraca.oranor; 
    display 'Number of SQL statement parses:     ', oraca.oranpr; 
    display 'Number of SQL statement executions: ', oraca.oranex; 
    exit program with an error; 
END sql_error;




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