JDBC Reference Information

A JDBC Reference Information

This appendix contains detailed Java Database Connectivity (JDBC) reference information, including the following topics:

A.1 Supported SQL-JDBC Data Type Mappings

The following table lists all the possible Java types to which a given SQL data type can be validly mapped. Oracle JDBC drivers will support these nondefault mappings. For example, to materialize SQL CHAR data in an oracle.sql.CHAR object, use the getCHAR method. To materialize it as a java.math.BigDecimal object, use the getBigDecimal method.

Note:

The classes, where oracle.jdbc.OracleData appears in italic, can be generated by Oracle JVM Web Services Call-Out Utility.

Table A-1 Valid SQL Data Type-Java Class Mappings

SQL data type	Java types
`CHAR`, `VARCHAR2`, `LONG`	`java.lang.String` `oracle.sql.CHAR`
`NUMBER`	`boolean` `char` `byte` `short` `int` `long` `float` `double` `java.lang.Byte` `java.lang.Short` `java.lang.Integer` `java.lang.Long` `java.lang.Float` `java.lang.Double` `java.math.BigDecimal` `oracle.sql.NUMBER`
`BINARY_INTEGER`	`boolean` `char` `byte` `short` `int` `long`
`BINARY_FLOAT`	`oracle.sql.BINARY_FLOAT`
`BINARY_DOUBLE`	`oracle.sql.BINARY_DOUBLE`
`DATE`	`oracle.sql.DATE`
`RAW`	`oracle.sql.RAW`
`BLOB`	`oracle.jdbc.OracleBlob`^Foot 1
`CLOB`	`oracle.jdbc.OracleClob`^Foot 2
`BFILE`	`oracle.sql.BFILE`
`ROWID`	`oracle.sql.ROWID`
`TIMESTAMP`	`oracle.sql.TIMESTAMP`
`TIMESTAMP WITH TIME ZONE`	`oracle.sql.TIMESTAMPTZ`
`TIMESTAMP WITH LOCAL TIME ZONE`	`oracle.sql.TIMESTAMPLTZ`
ref cursor	j`ava.sql.ResultSet` `sqlj.runtime.ResultSetIterator`
user defined named types, ADTs	`oracle.jdbc.OracleStruct`^Foot 3
opaque named types	`oracle.jdbc.OracleOpaque`^Foot 4
nested tables and VARRAY named types	`oracle.jdbc.OracleArray`^Foot 5
references to named types	`oracle.jdbc.OracleRef`^Foot 6

^Footnote 1

Starting from Oracle Database 12c Release 1 (12.1), the oracle.sql.BLOB class is deprecated and replaced with the oracle.jdbc.OracleBlob interface.

^Footnote 2

Starting from Oracle Database 12c Release 1 (12.1), the oracle.sql.CLOB class is deprecated and replaced with the oracle.jdbc.OracleClob interface.

^Footnote 3

Starting from Oracle Database 12c Release 1 (12.1), the oracle.sql.STRUCT class is deprecated and replaced with the oracle.jdbc.OracleStruct interface.

^Footnote 4

Starting from Oracle Database 12c Release 1 (12.1), the oracle.sql.OPAQUE class is deprecated and replaced with the oracle.jdbc.OracleOpaque interface.

^Footnote 5

Starting from Oracle Database 12c Release 1 (12.1), the oracle.sql.ARRAY class is deprecated and replaced with the oracle.jdbc.OracleArray interface.

^Footnote 6

Starting from Oracle Database 12c Release 1 (12.1), the oracle.sql.REF class is deprecated and replaced with the oracle.jdbc.OracleRef interface.

Note:

The type UROWID is not supported.
The oracle.sql.Datum class is abstract. The value passed to a parameter of type oracle.sql.Datum must be of the Java type corresponding to the underlying SQL type. Likewise, the value returned by a method with return type oracle.sql.Datum must be of the Java type corresponding to the underlying SQL type.

A.2 Supported SQL and PL/SQL Data Types

The tables in this section list SQL and PL/SQL data types, and Oracle JDBC driver support for them. The following table describes Oracle JDBC driver support for SQL data types.

Table A-2 Support for SQL Data Types

SQL Data Type	Supported by JDBC Drivers?
BFILE	yes
BLOB	yes
CHAR	yes
CLOB	yes
DATE	yes
NCHAR	no^Foot 7
NCHAR VARYING	no
NUMBER	yes
NVARCHAR2	yes^Foot 8
RAW	yes
REF	yes
ROWID	yes
UROWID	no
VARCHAR2	yes

^Footnote 7

The NCHAR type is supported indirectly. There is no corresponding java.sql.Types type, but if your application calls the formOfUse(NCHAR) method, then this type can be accessed.

^Footnote 8

In JSE 6, the NVARCHAR2 type is supported directly. In J2SE 5.0, the NVARCHAR2 type is supported indirectly. There is no corresponding java.sql.Types type, but if your application calls the formOfUse(NCHAR) method, then this type can be accessed.

The following table describes Oracle JDBC support for the ANSI-supported SQL data types.

Table A-3 Support for ANSI-92 SQL Data Types

ANSI-Supported SQL Data Type	Supported by JDBC Drivers?
CHARACTER	yes
DEC	yes
DECIMAL	yes
DOUBLE PRECISION	yes
FLOAT	yes
INT	yes
INTEGER	yes
NATIONAL CHARACTER	no
NATIONAL CHARACTER VARYING	no
NATIONAL CHAR	yes
NATIONAL CHAR VARYING	no
NCHAR	yes
NCHAR VARYING	no
NUMERIC	yes
REAL	yes
SMALLINT	yes
VARCHAR	yes

The following table describes Oracle JDBC driver support for SQL User-Defined types.

Table A-4 Support for SQL User-Defined Types

SQL User-Defined type	Supported by JDBC Drivers?
OPAQUE	yes
Reference types	yes
Object types (`JAVA_OBJECT`)	yes
Nested table types and VARRAY types	yes

The following table describes Oracle JDBC driver support for PL/SQL data types. The PL/SQL data types include the following categories:

Scalar types
Scalar character types, which includes DATE data type
Composite types
Reference types
Large object (LOB) types

Table A-5 Support for PL/SQL Data Types

PL/SQL Data Type	Supported by JDBC Drivers?
Scalar Types:
BINARY INTEGER	yes
DEC	yes
DECIMAL	yes
DOUBLE PRECISION	yes
FLOAT	yes
INT	yes
INTEGER	yes
NATURAL	yes
NATURALn	no
NUMBER	yes
NUMERIC	yes
PLS_INTEGER	yes
POSITIVE	yes
POSITIVEn	no
REAL	yes
SIGNTYPE	yes
SMALLINT	yes
BOOLEAN	yes
Scalar Character Types:
CHAR	yes
CHARACTER	yes
LONG	yes
LONG RAW	yes
NCHAR	no (see Note)
NVARCHAR2	no (see Note)
RAW	yes
ROWID	yes
STRING	yes
UROWID	no
VARCHAR	yes
VARCHAR2	yes
DATE	yes
Composite Types:
RECORD	no
TABLE	no
VARRAY	yes
Reference Types:
REF CURSOR types	yes
object reference types	yes
LOB Types:
BFILE	yes
BLOB	yes
CLOB	yes
NCLOB	yes

Note:

The types NATURAL, NATURALn, POSITIVE, POSITIVEn, and SIGNTYPE are subtypes of BINARY INTEGER.
The types DEC, DECIMAL, DOUBLE PRECISION, FLOAT, INT, INTEGER, NUMERIC, REAL, and SMALLINT are subtypes of NUMBER.
The types NCHAR and NVARCHAR2 are supported indirectly. There is no corresponding java.sql.Types type, but if your application calls formOfUse(NCHAR), then these types can be accessed.

Related Topics

NCHAR, NVARCHAR2, NCLOB and the defaultNChar Property

A.3 About Using PL/SQL Types

Starting from Oracle Database 12c Release 1 (12.1), you can map schema-level PL/SQL types as generic java.sql.Struct type and PL/SQL collections as java.sql.Array types. So, instead of creating schema-level types that are mapped to PL/SQL package types for binding, you can describe and bind PL/SQL types using only the JDBC APIs.

For example, you can call the Connection.createStruct(type_name) method to first create a descriptor that can be used to describe a PL/SQL type and then to create a new STRUCT representation of this type on the client. In Oracle Database 12c Release 1 (12.1), you can reuse this API by specifying type_name as “schema.package.typename" or “package.typename".

All PL/SQL package types are mapped to a system-wide unique name that can be used by JDBC to retrieve the server-side type metadata. The name is in the following form:

[SCHEMA.]<PACKAGE>.<TYPE>

Note:

If the schema is the same as the package name, and if there is a type with the same name as the PL/SQL type, then it will not be able to identify an object with the two part name format, that is, <package>.<type>. In such cases, you must use three part names <schema>.<package>.<type>.

The following code snippet explains how to bind types declared in PL/SQL packages:

/*
---------------------------
# Perform the following SQL operations prior to running this sample
---------------------------
conn HR/hr;
create or replace package TEST_PKG is
   type V_TYP is varray(10) of varchar2(200);
   type R_TYP is record(c1 pls_integer, c2 varchar2(100));
   procedure VARR_PROC(p1 in V_TYP, p2 OUT V_TYP);
   procedure REC_PROC(p1 in R_TYP, p2 OUT R_TYP);
end;
/
create or replace package body TEST_PKG is
 procedure VARR_PROC(p1 in V_TYP, p2 OUT V_TYP) is
  begin
    p2 := p1;
  end;
  procedure REC_PROC(p1 in R_TYP, p2 OUT R_TYP) is
  begin
    p2 := p1;
  end;
end;
/ 
*/

import java.sql.Array;
import java.sql.CallableStatement;
import java.sql.Connection;
import java.sql.SQLException;
import java.sql.Struct;
import java.sql.Types;
 
import oracle.jdbc.OracleConnection;
public class PLSQLTypesSample
{
  public static void main(String[] args) throws SQLException
  {
    System.out.println("begin...");
    Connection conn = null;
    oracle.jdbc.pool.OracleDataSource ods = new oracle.jdbc.pool.OracleDataSource();
    ods.setURL("jdbc:oracle:oci:localhost:5521:orcl");
    ods.setUser("HR");
    ods.setPassword("hr"); 
    //get connection
    conn = ods.getConnection();
 
    //call procedure TEST_PKG.VARR_PROC
    CallableStatement cstmt = null;
    try {
      cstmt = conn.prepareCall("{ call TEST_PKG.VARR_PROC(?,?) }");
      //PLSQL VARRAY type binding
      Array arr = ((OracleConnection)conn).createArray("TEST_PKG.V_TYP", new String[]{"A", "B"});
      cstmt.setArray(1, arr);
      cstmt.registerOutParameter(2, Types.ARRAY, "TEST_PKG.V_TYP");
      cstmt.execute();
      //get PLSQL VARRAY type out parameter value
      Array outArr = cstmt.getArray(2);
      //... 
    }
    catch( Exception e) {
      e.printStackTrace();
    }finally {
      if (cstmt != null)
        cstmt.close();
    }
 
    //call procedure TEST_PKG.REC_PROC
    try {
      cstmt = conn.prepareCall("{ call TEST_PKG.REC_PROC(?,?) }");
      //PLSQL RECORD type binding
      Struct struct = conn.createStruct("TEST_PKG.R_TYP", new Object[]{12345, "B"});
      cstmt.setObject(1, struct);
      cstmt.registerOutParameter(2, Types.STRUCT, "TEST_PKG.R_TYP");
      cstmt.execute();
      //get PLSQL RECORD type out parameter value
      Struct outStruct = (Struct)cstmt.getObject(2);
      //... 
    }
    catch( Exception e) {
      e.printStackTrace();
    }finally {
      if (cstmt != null)
        cstmt.close();
    }
    
    if (conn != null) 
      conn.close(); 
      
    System.out.println("done!");
  }
}

Creating Java level objects for each row using %ROWTYPE Attribute

You can create Java-level objects using the %ROWTYPE attribute. In this case, each row of the table is created as a java.sql.Struct object. For example, if you have a package pack1 with the following specification:

A.4 Using Embedded JDBC Escape Syntax

Oracle JDBC drivers support some embedded JDBC escape syntax, which is the syntax that you specify between curly braces. The current support is basic.

Note:

JDBC escape syntax was previously known as SQL92 Syntax or SQL92 escape syntax.

This section describes the support offered by the drivers for the following constructs:

Where driver support is limited, these sections also describe possible workarounds.

Disabling Escape Processing

The processing for JDBC escape syntax is enabled by default, which results in the JDBC driver performing escape substitution before sending the SQL code to the database. If you want the driver to use regular Oracle SQL syntax, which is more efficient than JDBC escape syntax processing, then use this statement:

stmt.setEscapeProcessing(false);

A.4.1 Time and Date Literals

Databases differ in the syntax they use for date, time, and timestamp literals. JDBC supports dates and times written only in a specific format. This section describes the formats you must use for date, time, and timestamp literals in SQL statements.

A.4.1.1 Date Literals

The JDBC drivers support date literals in SQL statements written in the format:

{d 'yyyy-mm-dd'}

Where yyyy-mm-dd represents the year, month, and day. For example:

{d '1995-10-22'}

The JDBC drivers will replace this escape clause with the equivalent Oracle representation: "22 OCT 1995".

The following code snippet contains an example of using a date literal in a SQL statement.

// Connect to the database
// You can put a database name after the @ sign in the connection URL.
OracleDataSource ods = new OracleDataSource();
ods.setURL("jdbc:oracle:oci:@");
ods.setUser("HR");
ods.setPassword("hr");
Connection conn = ods.getConnection();

// Create a Statement
Statement stmt = conn.createStatement ();

// Select the first name column from the employees table where the hire date is Jan-23-1982
ResultSet rset = stmt.executeQuery 
                 ("SELECT first_name FROM employees WHERE hire_date = {d '1982-01-23'}");

// Iterate through the result and print the employee names
while (rset.next ())
   System.out.println (rset.getString (1));

A.4.1.2 Time Literals

The JDBC drivers support time literals in SQL statements written in the format:

{t 'hh:mm:ss'}

where, hh:mm:ss represents the hours, minutes, and seconds. For example:

{t '05:10:45'}

The JDBC drivers will replace this escape clause with the equivalent Oracle representation: "05:10:45".

If the time is specified as:

{t '14:20:50'}

Then the equivalent Oracle representation would be "14:20:50", assuming the server is using a 24-hour clock.

This code snippet contains an example of using a time literal in a SQL statement.

ResultSet rset = stmt.executeQuery 
                 ("SELECT first_name FROM employees WHERE hire_date = {t '12:00:00'}");

A.4.1.3 Timestamp Literals

The JDBC drivers support timestamp literals in SQL statements written in the format:

{ts 'yyyy-mm-dd hh:mm:ss.f...'}

where yyyy-mm-dd hh:mm:ss.f... represents the year, month, day, hours, minutes, and seconds. The fractional seconds portion (.f...) is optional and can be omitted. For example: {ts '1997-11-01 13:22:45'} represents, in Oracle format, NOV 01 1997 13:22:45.

This code snippet contains an example of using a timestamp literal in a SQL statement.

ResultSet rset = stmt.executeQuery 
    ("SELECT first_name FROM employees WHERE hire_date = {ts '1982-01-23 12:00:00'}");

Mapping SQL DATE Data type to Java

Oracle Database 8i and earlier versions did not support TIMESTAMP data, but Oracle DATE data used to have a time component as an extension to the SQL standard. So, Oracle Database 8i and earlier versions of JDBC drivers mapped oracle.sql.DATE to java.sql.Timestamp to preserve the time component. Starting with Oracle Database 9.0.1, TIMESTAMP support was included and 9i JDBC drivers started mapping oracle.sql.DATE to java.sql.Date. This mapping was incorrect as it truncated the time component of Oracle DATE data. To overcome this problem, Oracle Database 11g Release 1 introduced a new flag mapDateToTimestamp. The default value of this flag is true, which means that by default the drivers will correctly map oracle.sql.DATE to java.sql.Timestamp, retaining the time information. If you still want the incorrect but 10g compatible oracle.sql.DATE to java.sql.Date mapping, then you can get it by setting the value of mapDateToTimestamp flag to false.

Note:

Since Oracle Database 11g, if you have an index on a DATE column to be used by a SQL query, then to obtain faster and accurate results, you must use the setObject method in the following way:
```
Date d = parseIsoDate(val);
Timestamp t = new Timestamp(d.getTime());
stmt.setObject(pos, new oracle.sql.DATE(t, (Calendar)UTC_CAL.clone()));
```
This is because if you use the setDate method, then the time component of the Oracle DATE data will be lost and if you use the setTimestamp method, then the index on the DATE column will not be used.
To overcome the problem of oracle.sql.DATE to java.sql.Date mapping, Oracle Database 9.2 introduced a flag, V8Compatible. The default value of this flag was false, which allowed the mapping of Oracle DATE data to java.sql.Date data. But, users could retain the time component of the Oracle DATE data by setting the value of this flag to true. This flag is desupported since 11g because it controlled Oracle Database 8i compatibility, which is no longer supported.

A.4.2 Scalar Functions

Oracle JDBC drivers do not support all scalar functions. To find out which functions the drivers support, use the following methods supported by the Oracle-specific oracle.jdbc.OracleDatabaseMetaData class and the standard Java java.sql.DatabaseMetadata interface:

getNumericFunctions()

Returns a comma-delimited list of math functions supported by the driver. For example, ABS, COS, SQRT.
getStringFunctions()

Returns a comma-delimited list of string functions supported by the driver. For example, ASCII, LOCATE.
getSystemFunctions()

Returns a comma-delimited list of system functions supported by the driver. For example, DATABASE, USER.
getTimeDateFunctions()

Returns a comma-delimited list of time and date functions supported by the driver. For example, CURDATE, DAYOFYEAR, HOUR.

Note:

Oracle JDBC drivers support fn, the function keyword.

A.4.3 LIKE Escape Characters

The characters % and _ have special meaning in SQL LIKE clauses. You use % to match zero or more characters and _ to match exactly one character. If you want to interpret these characters literally in strings, then you precede them with a special escape character. For example, if you want to use ampersand (&) as the escape character, then you identify it in the SQL statement as:

Statement stmt = conn.createStatement ();

// Select the empno column from the emp table where the ename starts with '_'
ResultSet rset = stmt.executeQuery
          ("SELECT empno FROM emp WHERE ename LIKE '&_%' {ESCAPE '&'}");

// Iterate through the result and print the employee numbers
while (rset.next ())
   System.out.println (rset.getString (1));

Note:

If you want to use the backslash character (\) as an escape character, then you must enter it twice, that is, \\. For example:

ResultSet rset = stmt.executeQuery("SELECT empno FROM emp
                WHERE ename LIKE '\\_%' {escape '\\'}");

A.4.4 MATCH_RECOGNIZE Clause

The ? character is used as a token in MATCH_RECOGNIZE clause in Oracle Database 11g and later versions. As the JDBC standard defines the ? character as a parameter marker, the JDBC Driver and the Server SQL Engine cannot distinguish between different uses of the same token.

In earlier versions of JDBC Driver, if you want to interpret the ? character as a MATCH_RECOGNIZE token and not as a parameter marker, then you must use a Statement instead of a PreparedStatement and disable escape processing. However, starting from Oracle Database 12c Release 1 (12.1.0.2), you can use the '{\\ ... \\}' syntax while using the ? character, so that the JDBC driver does not process it as a parameter marker and allows the SQL engine to process it. The following code snippet shows how to use the '{\\ ... \\}' syntax:

  String sql =
    "select T.firstW, T.lastZ, ? " +  // use of parameter marker
    "from tkpattern_S11 " +
    "MATCH_RECOGNIZE ( " +
    "    MEASURES A.c1 as firstW, last(Z.c1) as lastZ " +
    "    ALL MATCHES " +
    "    {\\ PATTERN(A? X*? Y+? Z??)\\} " +  // use of escape sequence
    "    DEFINE " +
    "        X as X.c2 > prev(X.c2), " +
    "        Y as Y.c2 < prev(Y.c2), " +
    "        Z as Z.c2 > prev(Z.c2)" +
    ") as T";
  PreparedStatement ps = conn.prepareStatatement(sql);
  ps.setString(1, "test");
  ResultSet rs = ps.executeQuery();

Related Topics

Using Embedded JDBC Escape Syntax

A.4.5 Outer Joins

Oracle JDBC drivers do not support the outer join syntax. The workaround is to use Oracle outer join syntax:

Instead of:

Statement stmt = conn.createStatement ();
ResultSet rset = stmt.executeQuery
     ("SELECT ename, dname 
       FROM {OJ dept LEFT OUTER JOIN emp ON dept.deptno = emp.deptno} 
       ORDER BY ename");

Use Oracle SQL syntax:

Statement stmt = conn.createStatement ();
ResultSet rset = stmt.executeQuery
     ("SELECT ename, dname 
       FROM emp b, dept a WHERE a.deptno = b.deptno(+)
       ORDER BY ename");

A.4.6 Function Call Syntax

Oracle JDBC drivers support the following procedure and function call syntax:

Procedure calls:

{ call procedure_name (argument1, argument2,...) }

Function calls:

{ ? = call procedure_name (argument1, argument2,...) }

A.4.7 JDBC Escape Syntax to Oracle SQL Syntax Example

You can write a simple program to translate JDBC escape syntax to Oracle SQL syntax. The following program prints the comparable Oracle SQL syntax for statements using JDBC escape syntax for function calls, date literals, time literals, and timestamp literals. In the program, the oracle.jdbc.OracleSql class parse() method performs the conversions.

public class Foo 
{ 
   static oracle.jdbc.OracleDriver driver = new oracle.jdbc.OracleDriver();
   public static void main (String args[]) throws Exception 
   { 
      show ("{call foo(?, ?)}"); 
      show ("{? = call bar (?, ?)}"); 
      show ("{d '1998-10-22'}"); 
      show ("{t '16:22:34'}"); 
      show ("{ts '1998-10-22 16:22:34'}"); 
   } 
 
   public static void show (String s) throws Exception 
   { 
      System.out.println (s + " => " + 
         driver.processSqlEscapes(s)); 
   } 
}

The following code is the output that prints the comparable SQL syntax.

{call foo(?, ?)} => BEGIN foo(:1, :2); END; 
{? = call bar (?, ?)} => BEGIN :1 := bar (:2, :3); END;
{d '1998-10-22'} => TO_DATE ('1998-10-22', 'YYYY-MM-DD')
{t '16:22:34'} => TO_DATE ('16:22:34', 'HH24:MI:SS')
{ts '1998-10-22 16:22:34'} => TO_TIMESTAMP ('1998-10-22 16:22:34', 'YYYY-MM-DD 
HH24:MI:SS.FF')

A.5 Oracle JDBC Notes and Limitations

The following limitations exist in the Oracle JDBC implementation, but all of them are either insignificant or have easy workarounds. This section covers the following topics:

A.5.1 CursorName

Oracle JDBC drivers do not support the getCursorName and setCursorName methods, because there is no convenient way to map them to Oracle constructs. Oracle recommends using ROWID instead.

Related Topics

Oracle ROWID Type

A.5.2 JDBC Outer Join Escapes

Oracle JDBC drivers do not support JDBC outer join escapes. Use Oracle SQL syntax with + instead.

Related Topics

Using Embedded JDBC Escape Syntax

A.5.3 IEEE 754 Floating Point Compliance

The arithmetic for the Oracle NUMBER type does not comply with the IEEE 754 standard for floating-point arithmetic. Therefore, there can be small disagreements between the results of computations performed by Oracle and the same computations performed by Java.

Oracle stores numbers in a format compatible with decimal arithmetic and guarantees 38 decimal digits of precision. It represents zero, minus infinity, and plus infinity exactly. For each positive number it represents, it represents a negative number of the same absolute value.

It represents every positive number between 10^-30 and (1 – 10^-38) * 10¹²⁶to full 38-digit precision.

A.5.4 Catalog Arguments to DatabaseMetaData Calls

Certain DatabaseMetaData methods define a catalog parameter. This parameter is one of the selection criteria for the method. Oracle does not have multiple catalogs, but it does have packages.

Related Topics

About Reporting DatabaseMetaData TABLE_REMARKS

A.5.5 SQLWarning Class

The java.sql.SQLWarning class provides information about a database access warning. Warnings typically contain a description of the warning and a code that identifies the warning. Warnings are silently chained to the object whose method caused it to be reported. Oracle JDBC drivers generally do not support SQLWarning. As an exception to this, scrollable result set operations do generate SQL warnings, but the SQLWarning instance is created on the client, not in the database.

Related Topics

About Processing SQL Exceptions

A.5.6 Executing DDL Statements

You must execute Data Definition Language (DDL) statements with Statement objects. If you use PreparedStatements objects or CallableStatements objects, then the DDL statement takes effect only on the first execution. This can cause unexpected behavior if the SQL statements are in a statement cache.

A.5.7 Binding Named Parameters

Binding by name is not supported when using the setXXX methods. Under certain circumstances, previous versions of Oracle JDBC drivers have allowed binding statement variables by name when using the setXXX methods. In the following statement, the named variable EmpId would be bound to the integer 314159.

PreparedStatement p = conn.prepareStatement
  ("SELECT name FROM emp WHERE id = :EmpId");
  p.setInt(1, 314159);

This capability to bind by name using the setXXX methods is not part of the JDBC specification, and Oracle does not support it. The JDBC drivers can throw a SQLException or produce unexpected results. Starting from Oracle Database 10g JDBC drivers, bind by name is supported using the setXXXAtName methods.

The bound values are not copied by the drivers until you call the execute method. So, changing the bound value before calling the execute method could change the bound value. For example, consider the following code snippet:

PreparedStatement p;
.......
Date d = new Date(1181676033917L);
p.setDate(1, d);
d.setTime(0);
p.executeUpdate();

This code snippet inserts Date(0) in the database instead of Date(1181676033917L) because the bound values are not copied by JDBC driver implementation for performance reasons.

Related Topics