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Oracle® Call Interface Programmer's Guide
11g Release 2 (11.2)

E10646-15
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Bind, Define, and Describe Functions

Table 16-4 lists the bind, define, and describe functions that are described in this section.

Table 16-4 Bind, Define, and Describe Functions 

Function Purpose

"OCIBindArrayOfStruct()"

Set skip parameters for static array bind

"OCIBindByName()"

Bind by name

"OCIBindByPos()"

Bind by position

"OCIBindDynamic()"

Set additional attributes after bind with OCI_DATA_AT_EXEC mode

"OCIBindObject()"

Set additional attributes for bind of named data type

"OCIDefineArrayOfStruct()"

Set additional attributes for static array define

"OCIDefineByPos()"

Define an output variable association

"OCIDefineDynamic()"

Set additional attributes for define in OCI_DYNAMIC_FETCH mode

"OCIDefineObject()"

Set additional attributes for define of named data type

"OCIDescribeAny()"

Describe existing schema objects

"OCIStmtGetBindInfo()"

Get bind and indicator variable names and handle


OCIBindArrayOfStruct()

Purpose

Sets up the skip parameters for a static array bind.

Syntax

sword OCIBindArrayOfStruct ( OCIBind     *bindp,
                             OCIError    *errhp,
                             ub4         pvskip, 
                             ub4         indskip, 
                             ub4         alskip, 
                             ub4         rcskip );

Parameters

bindp (IN/OUT)

The handle to a bind structure.

errhp (IN/OUT)

An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.

pvskip (IN)

Skip parameter for the next data value.

indskip (IN)

Skip parameter for the next indicator value or structure.

alskip (IN)

Skip parameter for the next actual length value.

rcskip (IN)

Skip parameter for the next column-level return code value.

Comments

This call sets up the skip parameters necessary for a static array bind. It follows a call to OCIBindByName() or OCIBindByPos(). The bind handle returned by that initial bind call is used as a parameter for the OCIBindArrayOfStruct() call.

See Also:

"Binding and Defining Arrays of Structures in OCI" for information about skip parameters

Related Functions

OCIBindByName(), OCIBindByPos()

OCIBindByName()

Purpose

Creates an association between a program variable and a placeholder in a SQL statement or PL/SQL block.

Syntax

sword OCIBindByName ( OCIStmt       *stmtp, 
                      OCIBind       **bindpp,
                      OCIError      *errhp,
                      const OraText *placeholder,
                      sb4           placeh_len,
                      void          *valuep,
                      sb4           value_sz,
                      ub2           dty,
                      void          *indp,
                      ub2           *alenp,
                      ub2           *rcodep,
                      ub4           maxarr_len,
                      ub4           *curelep, 
                      ub4           mode ); 

Parameters

stmtp (IN/OUT)

The statement handle to the SQL or PL/SQL statement being processed.

bindpp (IN/OUT)

A pointer to save the pointer of a bind handle that is implicitly allocated by this call. The bind handle maintains all the bind information for this particular input value. The default encoding for the call depends on the UTF-16 setting in stmtp unless the mode parameter has a different value. The handle is freed implicitly when the statement handle is deallocated. On input, the value of the pointer must be NULL or a valid bind handle.

errhp (IN/OUT)

An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.

placeholder (IN)

The placeholder, specified by its name, that maps to a variable in the statement associated with the statement handle. The encoding of placeholder should always be consistent with that of the environment. That is, if the statement is prepared in UTF-16, so is the placeholder. As a string type parameter, the placeholder should be cast as (text *) and terminated with NULL.

placeh_len (IN)

The length of the name specified in placeholder, in number of bytes regardless of the encoding.

valuep (IN/OUT)

The pointer to a data value or an array of data values of type specified in the dty parameter. This data could be a UTF-16 (formerly known as UCS-2) string, if an OCIAttrSet() function has been called to set OCI_ATTR_CHARSET_ID as OCI_UTF16ID or the deprecated OCI_UCS2ID. OCI_UTF16ID is the new designation for OCI_UCS2ID.

Furthermore, as pointed out for OCIStmtPrepare(), the default encoding for the string type valuep is in the encoding specified by the charset parameter of a previous call to OCIEnvNlsCreate(), unless users call OCIAttrSet() to manually reset the character set for the bind handle.

An array of data values can be specified for mapping into a PL/SQL table or for providing data for SQL multiple-row operations. When an array of bind values is provided, this is called an array bind in OCI terms.

For SQLT_NTY or SQLT_REF binds, the valuep parameter is ignored. The pointers to OUT buffers are set in the pgvpp parameter initialized by OCIBindObject().

When mode is set to OCI_IOV, pass the base address of the OCIIOV struct.

value_sz (IN)

The maximum size possible in bytes of any data value (passed using valuep) for this bind variable. This size is always expected to be the size in bytes. In the case of an array bind, this is the maximum size of any element possible with the actual sizes being specified in the alenp parameter.

For descriptors, locators, or REFs, whose size is unknown to client applications, use the size of the pointer to the specific type; for example, sizeof (OCILobLocator *).

The same applies even when mode is OCI_IOV.

dty (IN)

The data type of the values being bound. Named data types (SQLT_NTY) and REFs (SQLT_REF) are valid only if the application has been initialized in object mode. For named data types or REFs, additional calls must be made with the bind handle to set up the data type-specific attributes.

indp (IN/OUT)

Pointer to an indicator variable or array. For all data types except SQLT_NTY, this is a pointer to sb2 or an array of sb2.

For SQLT_NTY, this pointer is ignored, and the actual pointer to the indicator structure or an array of indicator structures is initialized in a subsequent call to OCIBindObject(). This parameter is ignored for dynamic binds.

alenp (IN/OUT)

Pointer to the array of actual lengths of array elements.

When OCIEnvNlsCreate() (which is the recommended OCI environment handle creation interface) is used, then alenp lengths are consistently expected in bytes (for IN binds) and reported in bytes for OUT binds. The same treatment consistently also holds for the length prefix in SQLT_VCS (2-byte length prefix) and SQLT_LVC (4-byte length prefix) types. There are no special exceptions for UCS2 or for NCHAR cases.

When the older OCI environment handle creation interfaces are used (either OCIEnvCreate()) or deprecated OCIEnvInit()), alenp lengths are in bytes in general. However, alenp lengths are expected in characters for IN binds and also reported in characters for OUT binds only when either the character set is OCI_UC2ID (= OCI_UTF16ID) or when OCI_ATTR_CHAR_COUNT attribute is set on the corresponding OCIBind handle. The same treatment holds for the length prefix in SQLT_VCS (2-byte length prefix) and SQLT_LVC (4-byte length prefix) types.

This parameter is ignored for dynamic binds.

rcodep (OUT)

Pointer to the array of column-level return codes. This parameter is ignored for dynamic binds.

maxarr_len (IN)

A maximum array length parameter (the maximum possible number of elements the user's array can accommodate). Used only for PL/SQL indexed table bindings.

curelep (IN/OUT)

Current array length parameter (a pointer to the actual number of elements in the array before or after the execute operation). Used only for PL/SQL indexed table bindings.

mode (IN)

To maintain coding consistency, theoretically this parameter can take all three possible values used by OCIStmtPrepare(). Because the encoding of bind variables should always be same as that of the statement containing this variable, an error is raised if the user specifies an encoding other than that of the statement. So the recommended setting for mode is OCI_DEFAULT, which makes the bind variable have the same encoding as its statement.

The valid modes are:

  • OCI_DEFAULT - The default mode. The statement handle that stmtp uses whatever is specified by its parent environment handle.

  • OCI_BIND_SOFT - Soft bind mode. This mode increases the performance of the call. If this is the first bind or some input value like dty or value_sz is changed from the previous bind, this mode is ignored. An error is returned if the statement is not executed. Unexpected behavior results if the bind handle passed is not valid.

  • OCI_DATA_AT_EXEC - When this mode is selected, the value_sz parameter defines the maximum size of the data that can be provided at run time. The application must be ready to provide the OCI library runtime IN data buffers at any time and any number of times. Runtime data is provided in one of these two ways:

    • Callbacks using a user-defined function that must be registered with a subsequent call to OCIBindDynamic().

    • A polling mechanism using calls supplied by the OCI. This mode is assumed if no callbacks are defined.

      See Also:

      "Runtime Data Allocation and Piecewise Operations in OCI" for more information about using the OCI_DATA_AT_EXEC mode

    When mode is set to OCI_DATA_AT_EXEC, do not provide values for valuep, indp, alenp, and rcodep in the main call. Pass zeros (0) for indp and alenp. Provide the values through the callback function registered using OCIBindDynamic().

  • OCI_IOV - Bind noncontiguous addresses of data. The valuep parameter must be of the type OCIIOV *.

When the allocated buffers are not required anymore, they should be freed by the client.

Comments

This call is used to perform a basic bind operation. The bind creates an association between the address of a program variable and a placeholder in a SQL statement or PL/SQL block. The bind call also specifies the type of data that is being bound, and may also indicate the method by which data is provided at run time.

Encoding is determined by either the bind handle using the setting in the statement handle as default, or you can override the setting by specifying the mode parameter explicitly.

The OCIBindByName() also implicitly allocates the bind handle indicated by the bindpp parameter. If a non-NULL pointer is passed in **bindpp, the OCI assumes that this points to a valid handle that has been previously allocated with a call to OCIHandleAlloc() or OCIBindByName().

Data in an OCI application can be bound to placeholders statically or dynamically. Binding is static when all the IN bind data and the OUT bind buffers are well defined just before the execute. Binding is dynamic when the IN bind data and the OUT bind buffers are provided by the application on demand at execute time to the client library. Dynamic binding is indicated by setting the mode parameter of this call to OCI_DATA_AT_EXEC.

See Also:

"Runtime Data Allocation and Piecewise Operations in OCI" for more information about dynamic binding

Both OCIBindByName() and OCIBindByPos() take as a parameter a bind handle, which is implicitly allocated by the bind call A separate bind handle is allocated for each placeholder the application is binding.

Additional bind calls may be required to specify particular attributes necessary when binding certain data types or handling input data in certain ways:

  • If arrays of structures are being used, OCIBindArrayOfStruct() must be called to set up the necessary skip parameters.

  • If data is being provided dynamically at run time, and the application uses user-defined callback functions, OCIBindDynamic() must be called to register the callbacks.

  • If lengths in alenp greater than 64 Kilobytes (KB) are required, use OCIBindDynamic().

  • If a named data type is being bound, OCIBindObject() must be called to specify additional necessary information.

  • If a statement with the RETURNING clause is used, a call to OCIBindDynamic() must follow this call.

With IN binds, the values for each element of the array, the actual lengths of each element, and the actual array length must be set up before the call to OCIStmtExecute().

With OUT binds, the values for each element of the array, the actual lengths of each element, and the actual array length are returned from the server after the OCIStmtExecute() call.

OCIBindByPos()

Purpose

Creates an association between a program variable and a placeholder in a SQL statement or PL/SQL block.

Syntax

sword OCIBindByPos ( OCIStmt      *stmtp, 
                     OCIBind      **bindpp,
                     OCIError     *errhp,
                     ub4          position,
                     void         *valuep,
                     sb4          value_sz,
                     ub2          dty,
                     void         *indp,
                     ub2          *alenp,
                     ub2          *rcodep,
                     ub4          maxarr_len,
                     ub4          *curelep, 
                     ub4          mode );

Parameters

stmtp (IN/OUT)

The statement handle to the SQL or PL/SQL statement being processed.

bindpp (IN/OUT)

An address of a bind handle that is implicitly allocated by this call. The bind handle maintains all the bind information for this particular input value. The handle is freed implicitly when the statement handle is deallocated. On input, the value of the pointer must be NULL or a valid bind handle.

errhp (IN/OUT)

An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.

position (IN)

The placeholder attributes are specified by position if OCIBindByPos() is being called.

valuep (IN/OUT)

An address of a data value or an array of data values of the type specified in the dty parameter. An array of data values can be specified for mapping into a PL/SQL table or for providing data for SQL multiple-row operations. When an array of bind values is provided, this is called an array bind in OCI terms.

For a LOB, the buffer pointer must be a pointer to a LOB locator of type OCILobLocator. Give the address of the pointer.

For SQLT_NTY or SQLT_REF binds, the valuep parameter is ignored. The pointers to OUT buffers are set in the pgvpp parameter initialized by OCIBindObject().

If the OCI_ATTR_CHARSET_ID attribute is set to OCI_UTF16ID (replaces the deprecated OCI_UCS2ID, which is retained for backward compatibility), all data passed to and received with the corresponding bind call is assumed to be in UTF-16 encoding.

When mode is set to OCI_IOV, pass the base address of the OCIIOV struct.

value_sz (IN)

The maximum size possible in bytes of any data value (passed using valuep) for this bind variable. This size is always expected to be the size in bytes. In the case of an array bind, this is the maximum size of any element possible with the actual sizes being specified in the alenp parameter.

For descriptors, locators, or REFs, whose size is unknown to client applications, use the size of the pointer to the specific type; for example, sizeof (OCILobLocator *).

The same applies even when mode is OCI_IOV.

dty (IN)

The data type of the values being bound. Named data types (SQLT_NTY) and REFs (SQLT_REF) are valid only if the application has been initialized in object mode. For named data types or REFs, additional calls must be made with the bind handle to set up the attributes specific to the data type.

indp (IN/OUT)

Pointer to an indicator variable or array. For all data types, this is a pointer to sb2 or an array of sb2 values. The only exception is SQLT_NTY, where this pointer is ignored and the actual pointer to the indicator structure or an array of indicator structures is initialized by OCIBindObject(). The indp parameter is ignored for dynamic binds. If valuep is an OUT parameter, then you must set indp to point to OCI_IND_NULL.

alenp (IN/OUT)

Pointer to an array of actual lengths of array elements.

When OCIEnvNlsCreate() (which is the recommended OCI environment handle creation interface) is used, then alenp lengths are consistently expected in bytes (for IN binds) and reported in bytes for OUT binds. The same treatment consistently also holds for the length prefix in SQLT_VCS (2-byte length prefix) and SQLT_LVC (4-byte length prefix) types. There are no special exceptions for UCS2 or for NCHAR cases.

When the older OCI environment handle creation interfaces are used (either OCIEnvCreate() or deprecated OCIEnvInit()), alenp lengths are in bytes in general. However, alenp lengths are expected in characters for IN binds and also reported in characters for OUT binds only when either the character set is OCI_UC2ID (= OCI_UTF16ID) or when OCI_ATTR_CHAR_COUNT attribute is set on the corresponding OCIBind handle. The same treatment holds for the length prefix in SQLT_VCS (2-byte length prefix) and SQLT_LVC (4-byte length prefix) types.

This parameter is ignored for dynamic binds.

rcodep (OUT)

Pointer to an array of column-level return codes. This parameter is ignored for dynamic binds.

maxarr_len (IN)

A maximum array length parameter (the maximum possible number of elements that the user's array can accommodate). Used only for PL/SQL indexed table bindings.

curelep (IN/OUT)

Current array length parameter (a pointer to the actual number of elements in the array before or after the execute operation). Used only for PL/SQL indexed table bindings.

mode (IN)

The valid modes for this parameter are:

  • OCI_DEFAULT - This is default mode.

  • OCI_BIND_SOFT - Soft bind mode. This mode increases the performance of the call. If this is the first bind or some input value like dty or value_sz is changed from the previous bind, this mode is ignored. An error is returned if the statement is not executed. Unexpected behavior results if the bind handle passed is not valid.

  • OCI_DATA_AT_EXEC - When this mode is selected, the value_sz parameter defines the maximum size of the data that can be provided at run time. The application must be ready to provide the OCI library runtime IN data buffers at any time and any number of times. Runtime data is provided in one of the following ways:

    • Callbacks using a user-defined function that must be registered with a subsequent call to OCIBindDynamic().

    • A polling mechanism using calls supplied by OCI. This mode is assumed if no callbacks are defined.

      See Also:

      "Runtime Data Allocation and Piecewise Operations in OCI" for more information about using the OCI_DATA_AT_EXEC mode

      When mode is set to OCI_DATA_AT_EXEC, do not provide values for valuep, indp, alenp, and rcodep in the main call. Pass zeros (0) for indp and alenp. Provide the values through the callback function registered using OCIBindDynamic().

  • OCI_IOV - Bind noncontiguous addresses of data. The valuep parameter must be of the type OCIIOV *.

When the allocated buffers are not required anymore, they should be freed by the client.

Comments

This call is used to perform a basic bind operation. The bind creates an association between the address of a program variable and a placeholder in a SQL statement or PL/SQL block. The bind call also specifies the type of data that is being bound, and may also indicate the method by which data is to be provided at run time.

This function also implicitly allocates the bind handle indicated by the bindpp parameter. If a non-NULL pointer is passed in **bindpp, OCI assumes that this points to a valid handle that has been previously allocated with a call to OCIHandleAlloc() or OCIBindByPos().

Data in an OCI application can be bound to placeholders statically or dynamically. Binding is static when all the IN bind data and the OUT bind buffers are well defined just before the execute operation. Binding is dynamic when the IN bind data and the OUT bind buffers are provided by the application on demand at execute time to the client library. Dynamic binding is indicated by setting the mode parameter of this call to OCI_DATA_AT_EXEC.

See Also:

"Runtime Data Allocation and Piecewise Operations in OCI" for more information about dynamic binding

Both OCIBindByName() and OCIBindByPos() take as a parameter a bind handle, which is implicitly allocated by the bind call A separate bind handle is allocated for each placeholder the application is binding.

Additional bind calls may be required to specify particular attributes necessary when binding certain data types or handling input data in certain ways:

  • If arrays of structures are being used, OCIBindArrayOfStruct() must be called to set up the necessary skip parameters.

  • If data is being provided dynamically at run time, and the application uses user-defined callback functions, OCIBindDynamic() must be called to register the callbacks.

  • If lengths in alenp greater than 64 KB are required, use OCIBindDynamic().

  • If a named data type is being bound, OCIBindObject() must be called to specify additional necessary information.

  • If a statement with the RETURNING clause is used, a call to OCIBindDynamic() must follow this call.

With IN binds, the values for each element of the array, the actual lengths of each element, and the actual array length must be set up before the call to OCIStmtExecute().

With OUT binds, the values for each element of the array, the actual lengths of each element, and the actual array length are returned from the server after the OCIStmtExecute() call.

OCIBindDynamic()

Purpose

Registers user callbacks for dynamic data allocation.

Syntax

sword OCIBindDynamic ( OCIBind     *bindp,
                       OCIError    *errhp,
                       void        *ictxp, 
                       OCICallbackInBind         (icbfp)(
                                void             *ictxp,
                                OCIBind          *bindp,
                                ub4              iter, 
                                ub4              index, 
                                void             **bufpp,
                                ub4              *alenp,
                                ub1              *piecep, 
                                void             **indpp ),
                                void             *octxp,
                       OCICallbackOutBind        (ocbfp)(
                                void             *octxp,
                                OCIBind          *bindp,
                                ub4              iter, 
                                ub4              index, 
                                void             **bufpp, 
                                ub4              **alenpp,
                                ub1              *piecep,
                                void             **indpp, 
                                ub2              **rcodepp ) );

Parameters

bindp (IN/OUT)

A bind handle returned by a call to OCIBindByName() or OCIBindByPos().

errhp (IN/OUT)

An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.

ictxp (IN)

The context pointer required by the callback function icbfp.

icbfp (IN)

The callback function that returns a pointer to the IN bind value or piece at run time. The callback takes in the following parameters:

ictxp (IN/OUT)

The context pointer for this callback function.

bindp (IN)

The bind handle passed in to uniquely identify this bind variable.

iter (IN)

A 0-based execute iteration value.

index (IN)

Index of the current array, for an array bind in PL/SQL. For SQL it is the row index. The value is 0-based and not greater than the curelep parameter of the bind call.

bufpp (OUT)

The pointer to the buffer or storage. For descriptors, *bufpp contains a pointer to the descriptor. For example, if you define the following parameter, then you set *bufpp to lobp, not *lobp.

OCILobLocator    *lobp;

For REFs, pass the address of the ref; that is, pass &my_ref for *bufpp.

If the OCI_ATTR_CHARSET_ID attribute is set to OCI_UTF16ID (replaces the deprecated OCI_UCS2ID, which is retained for backward compatibility), all data passed to and received with the corresponding bind call is assumed to be in UTF-16 encoding.

alenp (OUT)

A pointer to storage for OCI to fill in the size of the bind value or piece after it has been read. For descriptors, pass the size of the pointer to the descriptor; for example, sizeof(OCILobLocator *).

piecep (OUT)

A piece of the bind value. This can be one of the following values: OCI_ONE_PIECE, OCI_FIRST_PIECE, OCI_NEXT_PIECE, and OCI_LAST_PIECE. For data types that do not support piecewise operations, you must pass OCI_ONE_PIECE or an error is generated.

indpp (OUT)

Contains the indicator value. This is either a pointer to an sb2 value or a pointer to an indicator structure for binding named data types.

octxp (IN)

The context pointer required by the callback function ocbfp().

ocbfp (IN)

The callback function that returns a pointer to the OUT bind value or piece at run time. The callback takes in the following parameters:

octxp (IN/OUT)

The context pointer for this callback function.

bindp (IN)

The bind handle passed in to uniquely identify this bind variable.

iter (IN)

A 0-based execute iteration value.

index (IN)

For PL/SQL, the index of the current array for an array bind. For SQL, the index is the row number in the current iteration. It is 0-based, and must not be greater than the curelep parameter of the bind call.

bufpp (OUT)

A pointer to a buffer to write the bind value or piece in.

If the OCI_ATTR_CHARSET_ID attribute is set to OCI_UTF16ID (replaces the deprecated OCI_UCS2ID, which is retained for backward compatibility), all data passed to and received with the corresponding bind call is assumed to be in UTF-16 encoding. For more information, see "Bind Handle Attributes".

alenpp (IN/OUT)

A pointer to storage for OCI to fill in the size of the bind value or piece after it has been read. It is in bytes except for Unicode encoding (if the OCI_ATTR_CHARSET_ID attribute is set to OCI_UTF16ID), when it is in code points.

piecep (IN/OUT)

Returns a piece value from the callback (application) to the Oracle Database, as follows:

  • IN - The value can be OCI_ONE_PIECE or OCI_NEXT_PIECE.

  • OUT - Depends on the IN value:

    • If IN value is OCI_ONE_PIECE, then OUT value can be OCI_ONE_PIECE or OCI_FIRST_PIECE.

    • If IN value is OCI_NEXT_PIECE, then OUT value can be OCI_NEXT_PIECE or OCI_LAST_PIECE.

indpp (OUT)

Contains the indicator value. This is either a pointer to an sb2 value, or a pointer to an indicator structure for binding named data types.

rcodepp (OUT)

Returns a pointer to the return code.

Comments

This call is used to register user-defined callback functions for providing or receiving data if OCI_DATA_AT_EXEC mode was specified in a previous call to OCIBindByName() or OCIBindByPos().

The callback function pointers must return OCI_CONTINUE if the call is successful. Any return code other than OCI_CONTINUE signals that the client wants to terminate processing immediately.

See Also:

"Runtime Data Allocation and Piecewise Operations in OCI" for more information about the OCI_DATA_AT_EXEC mode

When passing the address of a storage area, ensure that the storage area exists even after the application returns from the callback. This means that you should not allocate such storage on the stack.

Note:

After you use OCIEnvNlsCreate() to create the environment handle, the actual lengths and returned lengths of bind and define handles are always in number of bytes.

Related Functions

OCIBindByName(), OCIBindByPos()

OCIBindObject()

Purpose

Sets up additional attributes that are required for a named data type (object) bind.

Syntax

sword OCIBindObject ( OCIBind          *bindp,
                      OCIError         *errhp, 
                      const OCIType    *type,
                      void             **pgvpp, 
                      ub4              *pvszsp, 
                      void             **indpp, 
                      ub4              *indszp, );

Parameters

bindp (IN/OUT)

The bind handle returned by the call to OCIBindByName() or OCIBindByPos().

errhp (IN/OUT)

An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.

type (IN)

Points to the TDO that describes the type of program variable being bound. Retrieved by calling OCITypeByName(). Optional for REFs in SQL, but required for REFs in PL/SQL.

pgvpp (IN/OUT)

Address of the program variable buffer. For an array, pgvpp points to an array of addresses. When the bind variable is also an OUT variable, the OUT named data type value or REF is allocated in the Object Cache, and a REF is returned.

pgvpp is ignored if the OCI_DATA_AT_EXEC mode is set. Then the named data type buffers are requested at run time. For static array binds, skip factors may be specified using the OCIBindArrayOfStruct() call. The skip factors are used to compute the address of the next pointer to the value, the indicator structure, and their sizes.

pvszsp (OUT) [optional]

Points to the size of the program variable. The size of the named data type is not required on input. For an array, pvszsp is an array of ub4s. On return, for OUT bind variables, this points to sizes of the named data types and REFs received. pvszsp is ignored if the OCI_DATA_AT_EXEC mode is set. Then the size of the buffer is taken at run time.

indpp (IN/OUT) [optional]

Address of the program variable buffer containing the parallel indicator structure. For an array, indpp points to an array of pointers. When the bind variable is also an OUT bind variable, memory is allocated in the object cache, to store the OUT indicator values. At the end of the execute operation when all OUT values have been received, indpp points to the pointers of these newly allocated indicator structures. Required only for SQLT_NTY binds. The indpp parameter is ignored if the OCI_DATA_AT_EXEC mode is set. Then the indicator is requested at run time.

indszp (IN/OUT)

Points to the size of the IN indicator structure program variable. For an array, it is an array of sb2s. On return for OUT bind variables, this points to sizes of the received OUT indicator structures. indszp is ignored if the OCI_DATA_AT_EXEC mode is set. Then the indicator size is requested at run time.

Comments

This function sets up additional attributes for binding a named data type or a REF. An error is returned if this function is called when the OCI environment has been initialized in non-object mode.

This call takes as a parameter a type descriptor object (TDO) of data type OCIType for the named data type being defined. The TDO can be retrieved with a call to OCITypeByName().

If the OCI_DATA_AT_EXEC mode was specified in OCIBindByName() or OCIBindByPos(), the pointers to the IN buffers are obtained either using the callback icbfp registered in the OCIBindDynamic() call or by the OCIStmtSetPieceInfo() call.

The buffers are dynamically allocated for the OUT data. The pointers to these buffers are returned either by:

The memory of these client library-allocated buffers must be freed when not in use anymore by using the OCIObjectFree() call.

Related Functions

OCIBindByName(), OCIBindByPos()

OCIDefineArrayOfStruct()

Purpose

Specifies additional attributes necessary for a static array define, used in an array of structures (multirow, multicolumn) fetch.

Syntax

sword OCIDefineArrayOfStruct ( OCIDefine   *defnp,
                               OCIError    *errhp,
                               ub4         pvskip, 
                               ub4         indskip, 
                               ub4         rlskip,
                               ub4         rcskip );

Parameters

defnp (IN/OUT)

The handle to the define structure that was returned by a call to OCIDefineByPos().

errhp (IN/OUT)

An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.

pvskip (IN)

Skip parameter for the next data value.

indskip (IN)

Skip parameter for the next indicator location.

rlskip (IN)

Skip parameter for the next return length value.

rcskip (IN)

Skip parameter for the next return code.

Comments

This call follows a call to OCIDefineByPos(). If the application is binding an array of structures involving objects, it must call OCIDefineObject() first, and then call OCIDefineArrayOfStruct().

Related Functions

OCIDefineByPos(), OCIDefineObject()

OCIDefineByPos()

Purpose

Associates an item in a select list with the type and output data buffer.

Syntax

sword OCIDefineByPos ( OCIStmt     *stmtp, 
                       OCIDefine   **defnpp,
                       OCIError    *errhp,
                       ub4         position,
                       void        *valuep,
                       sb4         value_sz,
                       ub2         dty,
                       void        *indp,
                       ub2         *rlenp,
                       ub2         *rcodep,
                       ub4         mode );

Parameters

stmtp (IN/OUT)

A handle to the requested SQL query operation.

defnpp (IN/OUT)

A pointer to a pointer to a define handle. If this parameter is passed as NULL, this call implicitly allocates the define handle. For a redefine, a non-NULL handle can be passed in this parameter. This handle is used to store the define information for this column.

Note:

The user must keep track of this pointer. If a second call to OCIDefineByPos() is made for the same column position, there is no guarantee that the same pointer will be returned.
errhp (IN/OUT)

An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.

position (IN)

The position of this value in the select list. Positions are 1-based and are numbered from left to right. The value 0 selects ROWIDs (the globally unique identifier for a row in a table).

valuep (IN/OUT)

A pointer to a buffer or an array of buffers of the type specified in the dty parameter. A number of buffers can be specified when results for more than one row are desired in a single fetch call.

For a LOB, the buffer pointer must be a pointer to a LOB locator of type OCILobLocator. Give the address of the pointer.

When mode is set to OCI_IOV, pass the base address of the OCIIOV struct.

value_sz (IN)

The size of each valuep buffer in bytes. If the data is stored internally in VARCHAR2 format, the number of characters desired, if different from the buffer size in bytes, may be additionally specified by using OCIAttrSet().

In a multibyte conversion environment, a truncation error is generated if the number of bytes specified is insufficient to handle the number of characters needed.

If the OCI_ATTR_CHARSET_ID attribute is set to OCI_UTF16ID (replaces the deprecated OCI_UCS2ID, which is retained for backward compatibility), all data passed to and received with the corresponding define call is assumed to be in UTF-16 encoding.

When mode is set to OCI_IOV, pass the size of the data value.

dty (IN)

The data type. Named data type (SQLT_NTY) and REF (SQLT_REF) are valid only if the environment has been initialized in object mode.

SQLT_CHR and SQLT_LNG can be specified for CLOB columns, and SQLT_BIN and SQLT_LBI can be specified for BLOB columns.

See Also:

Chapter 3 for a listing of data type codes and values
indp (IN)

Pointer to an indicator variable or array. For scalar data types, pointer to sb2 or an array of sb2s. Ignored for SQLT_NTY defines. For SQLT_NTY defines, a pointer to a named data type indicator structure or an array of named data type indicator structures is associated by a subsequent OCIDefineObject() call.

rlenp (IN/OUT)

Pointer to array of length of data fetched.

When OCIEnvNlsCreate() (which is the recommended OCI environment handle creation interface) is used, then rlenp lengths are consistently reported in bytes. The same treatment consistently also holds for the length prefix in SQLT_VCS (2-byte length prefix) and SQLT_LVC (4-byte length prefix) types. There are no special exceptions for UCS2 or for NCHAR cases.

When the older OCI environment handle creation interfaces are used (either OCIEnvCreate() or deprecated OCIEnvInit()), rlenp lengths are in bytes in general. However, rlenp lengths are reported in characters when either the character set is OCI_UC2ID (= OCI_UTF16ID) or when OCI_ATTR_CHAR_COUNT attribute is set on the corresponding OCIBind handle. The same treatment holds for the length prefix in SQLT_VCS (2-byte length prefix) and SQLT_LVC (4-byte length prefix) types.

rcodep (OUT)

Pointer to array of column-level return codes.

mode (IN)

The valid modes are:

  • OCI_DEFAULT - This is the default mode.

  • OCI_DEFINE_SOFT - Soft define mode. This mode increases the performance of the call. If this is the first define, or some input parameter such as dty or value_sz is changed from the previous define, this mode is ignored. Unexpected behavior results if an invalid define handle is passed. An error is returned if the statement is not executed.

  • OCI_DYNAMIC_FETCH - For applications requiring dynamically allocated data at the time of fetch, this mode must be used. You can define a callback using the OCIDefineDynamic() call. The value_sz parameter defines the maximum size of the data that is to be provided at run time. When the client library needs a buffer to return the fetched data, the callback is invoked to provide a runtime buffer into which a piece or all the data is returned.

  • OCI_IOV - Define noncontiguous addresses of data. The valuep parameter must be of the type OCIIOV *.

Comments

This call defines an output buffer that receives data retrieved from Oracle Database. The define is a local step that is necessary when a SELECT statement returns data to your OCI application.

This call also implicitly allocates the define handle for the select-list item. If a non-NULL pointer is passed in *defnpp, OCI assumes that this points to a valid handle that has been previously allocated with a call to OCIHandleAlloc() or OCIDefineByPos(). This would be true for an application that is redefining a handle to a different address so that it can reuse the same define handle for multiple fetches.

Defining attributes of a column for a fetch is done in one or more calls. The first call is to OCIDefineByPos(), which defines the minimal attributes required to specify the fetch.

Following the call to OCIDefineByPos() additional define calls may be necessary for certain data types or fetch modes:

  • A call to OCIDefineArrayOfStruct() is necessary to set up skip parameters for an array fetch of multiple columns.

  • A call to OCIDefineObject() is necessary to set up the appropriate attributes of a named data type (that is, object or collection) or REF fetch. In this case, the data buffer pointer in OCIDefineByPos() is ignored.

  • Both OCIDefineArrayOfStruct() and OCIDefineObject() must be called after OCIDefineByPos() to fetch multiple rows with a column of named data types.

For a LOB define, the buffer pointer must be a pointer to a LOB locator of type OCILobLocator, allocated by the OCIDescriptorAlloc() call. LOB locators, and not LOB values, are always returned for a LOB column. LOB values can then be fetched using OCI LOB calls on the fetched locator. This same mechanism applies for all descriptor data types.

For NCHAR (fixed and varying length), the buffer pointer must point to an array of bytes sufficient for holding the required NCHAR characters.

Nested table columns are defined and fetched like any other named data type.

When defining an array of descriptors or locators, you should pass in an array of pointers to descriptors or locators.

When doing an array define for character columns, you should pass in an array of character buffers.

If the mode parameter in this call is set to OCI_DYNAMIC_FETCH, the client application can fetch data dynamically at run time. Runtime data can be provided in one of two ways:

  • Callbacks using a user-defined function that must be registered with a subsequent call to OCIDefineDynamic(). When the client library needs a buffer to return the fetched data, the callback is invoked and the runtime buffers provided return a piece or all of the data.

  • A polling mechanism using calls supplied by OCI. This mode is assumed if no callbacks are defined. In this case, the fetch call returns the OCI_NEED_DATA error code, and a piecewise polling method is used to provide the data.

    See Also:

OCIDefineDynamic()

Purpose

Sets the additional attributes required if the OCI_DYNAMIC_FETCH mode was selected in OCIDefineByPos().

Syntax

sword OCIDefineDynamic ( OCIDefine   *defnp,
                         OCIError    *errhp,
                         void        *octxp, 
                         OCICallbackDefine       (ocbfp)(
                                  void           *octxp,
                                  OCIDefine      *defnp,
                                  ub4            iter, 
                                  void           **bufpp,
                                  ub4            **alenpp,
                                  ub1            *piecep,
                                  void           **indpp,
                                  ub2            **rcodep );

Parameters

defnp (IN/OUT)

The handle to a define structure returned by a call to OCIDefineByPos().

errhp (IN/OUT)

An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.

octxp (IN)

Points to a context for the callback function.

ocbfp (IN)

Points to a callback function. This is invoked at run time to get a pointer to the buffer into which the fetched data or a piece of it is to be retrieved. The callback also specifies the indicator, the return code, and the lengths of the data piece and indicator.

Caution:

Normally, in an OCI function, an IN parameter refers to data being passed to OCI, and an OUT parameter refers to data coming back from OCI. For callbacks, this is reversed. IN means that data is coming from OCI into the callback, and OUT means that data is coming out of the callback and going to OCI.

The callback parameters are:

octxp (IN/OUT)

A context pointer passed as an argument to all the callback functions. When the client library needs a buffer to return the fetched data, the callback is invoked and the runtime buffers provided return a piece or all of the data.

defnp (IN)

The define handle.

iter (IN)

Specifies which row of this current fetch; 0-based.

bufpp (OUT)

Returns a pointer to a buffer to store the column value; that is, *bufpp points to some appropriate storage for the column value.

alenpp (IN/OUT)

Used by the application to set the size of the storage it is providing in *bufpp. After data is fetched into the buffer, alenpp indicates the actual size of the data in bytes. If the buffer length provided in the first call is insufficient to store all the data returned by the server, then the callback is called again, and so on.

piecep (IN/OUT)

Returns a piece value from the callback (application) to OCI, as follows:

The piecep parameter indicates whether the piece to be fetched is the first piece, OCI_FIRST_PIECE, a subsequent piece, OCI_NEXT_PIECE, or the last piece, OCI_LAST_PIECE. The program can process the piece the next time the callback is called, or after the series of callbacks is over.

  • IN - The value can be OCI_ONE_PIECE, OCI_FIRST_PIECE, or OCI_NEXT_PIECE.

  • OUT - Depends on the IN value:

    • The OUT value can be OCI_ONE_PIECE if the IN value was OCI_ONE_PIECE.

    • The OUT value can be OCI_ONE_PIECE or OCI_FIRST_PIECE if the IN value was OCI_FIRST_PIECE.

    • The OUT value can be OCI_NEXT_PIECE or OCI_LAST_PIECE if the IN value was OCI_NEXT_PIECE.

indpp (IN)

Indicator variable pointer.

rcodep (IN)

Return code variable pointer.

Comments

This call is used to set the additional attributes required if the OCI_DYNAMIC_FETCH mode has been selected in a call to OCIDefineByPos(). If OCI_DYNAMIC_FETCH mode was selected, and the call to OCIDefineDynamic() is skipped, then the application can fetch data piecewise using OCI calls (OCIStmtGetPieceInfo() and OCIStmtSetPieceInfo()).

Note:

After you use OCIEnvNlsCreate() to create the environment handle, the actual lengths and returned lengths of bind and define handles are always in number of bytes.

See Also:

"Runtime Data Allocation and Piecewise Operations in OCI" for more information about OCI_DYNAMIC_FETCH mode

Related Functions

OCIDefineObject(), OCIBindDynamic()

OCIDefineObject()

Purpose

Sets up additional attributes necessary for a named data type or REF define.

Syntax

sword OCIDefineObject ( OCIDefine       *defnp,
                        OCIError        *errhp,
                        const OCIType   *type,
                        void            **pgvpp, 
                        ub4             *pvszsp, 
                        void            **indpp, 
                        ub4             *indszp );

Parameters

defnp (IN/OUT)

A define handle previously allocated in a call to OCIDefineByPos().

errhp (IN/OUT)

An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.

type (IN) [optional]

Points to the type descriptor object (TDO) that describes the type of the program variable. This parameter is optional for variables of type SQLT_REF, and may be passed as NULL if it is not being used.

pgvpp (IN/OUT)

Points to a pointer to a program variable buffer. For an array, pgvpp points to an array of pointers. Memory for the fetched named data type instances is dynamically allocated in the object cache. At the end of the fetch when all the values have been received, pgvpp points to the pointers to these newly allocated named data type instances. The application must call OCIObjectFree() to deallocate the named data type instances when they are no longer needed.

Note:

If the application wants the buffer to be implicitly allocated in the cache, *pgvpp should be passed in as NULL.
pvszsp (IN/OUT)

Points to the size of the program variable. For an array, it is an array of ub4.

indpp (IN/OUT)

Points to a pointer to the program variable buffer containing the parallel indicator structure. For an array, points to an array of pointers. Memory is allocated to store the indicator structures in the object cache. At the end of the fetch when all values have been received, indpp points to the pointers to these newly allocated indicator structures.

indszp (IN/OUT)

Points to the sizes of the indicator structure program variable. For an array, it is an array of ub4s.

Comments

This function follows a call to OCIDefineByPos() to set initial define information. This call sets up additional attributes necessary for a named data type define. An error is returned if this function is called when the OCI environment has been initialized in non-object mode.

This call takes as a parameter a type descriptor object (TDO) of data type OCIType for the named data type being defined. The TDO can be retrieved with a call to OCIDescribeAny().

See Also:

Related Functions

OCIDefineByPos()

OCIDescribeAny()

Purpose

Describes existing schema and subschema objects.

Syntax

sword OCIDescribeAny ( OCISvcCtx       *svchp,
                       OCIError        *errhp,
                       void            *objptr,
                       ub4             objptr_len,
                       ub1             objptr_typ,
                       ub1             info_level,
                       ub1             objtyp,
                       OCIDescribe     *dschp );

Parameters

svchp (IN)

A service context handle.

errhp (IN/OUT)

An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.

objptr (IN)

This parameter can be:

  1. A string containing the name of the object to be described. Must be in the encoding specified by the charset parameter of a previous call to OCIEnvNlsCreate().

  2. A pointer to a REF to the TDO (for a type).

  3. A pointer to a TDO (for a type).

These cases are distinguished by passing the appropriate value for objptr_typ. This parameter must be non-NULL.

In case 1, the string containing the object name should be in the format name1[.name2 ...][@linkname], such as hr.employees.employee_id@mydb. Database links are only allowed to Oracle8i or later databases. The object name is interpreted by the following SQL rules:

  • If only name1 is entered and objtyp is equal to OCI_PTYPE_SCHEMA, then the name refers to the named schema. The Oracle Database must be release 8.1 or later.

  • If only name1 is entered and objtyp is equal to OCI_PTYPE_DATABASE, then the name refers to the named database. When describing a remote database with database_name@db_link_name, the remote Oracle Database must be release 8.1 or later.

  • If only name1 is entered and objtyp is not equal to OCI_PTYPE_SCHEMA or OCI_PTYPE_DATABASE, then the name refers to the named object (of type table, view, procedure, function, package, type, synonym, sequence) in the current schema of the current user. When connected to an Oracle7 Server, the only valid types are procedure and function.

  • If name1.name2.name3 ... is entered, the object name refers to a schema or subschema object in the schema named name1. For example, in the string hr.employees.department_id, hr is the name of the schema, employees is the name of a table in the schema, and department_id is the name of a column in the table.

objnm_len (IN)

The length of the name string pointed to by objptr. Must be nonzero if a name is passed. Can be zero if objptr is a pointer to a TDO or its REF.

objptr_typ (IN)

The type of object passed in objptr. Valid values are:

  • OCI_OTYPE_NAME, if objptr points to the name of a schema object

  • OCI_OTYPE_REF, if objptr is a pointer to a REF to a TDO

  • OCI_OTYPE_PTR, if objptr is a pointer to a TDO

info_level (IN)

Reserved for future extensions. Pass OCI_DEFAULT.

objtyp (IN)

The type of schema object being described. Valid values are:

  • OCI_PTYPE_TABLE, for tables

  • OCI_PTYPE_VIEW, for views

  • OCI_PTYPE_PROC, for procedures

  • OCI_PTYPE_FUNC, for functions

  • OCI_PTYPE_PKG, for packages

  • OCI_PTYPE_TYPE, for types

  • OCI_PTYPE_SYN, for synonyms

  • OCI_PTYPE_SEQ, for sequences

  • OCI_PTYPE_SCHEMA, for schemas

  • OCI_PTYPE_DATABASE, for databases

  • OCI_PTYPE_UNK, for unknown schema objects

dschp (IN/OUT)

A describe handle that is populated with describe information about the object after the call. Must be non-NULL.

Comments

This is a generic describe call that describes existing schema objects: tables, views, synonyms, procedures, functions, packages, sequences, types, schemas, and databases. This call also describes subschema objects, such as a column in a table. This call populates the describe handle with the object-specific attributes that can be obtained through an OCIAttrGet() call.

An OCIParamGet() on the describe handle returns a parameter descriptor for a specified position. Parameter positions begin with 1. Calling OCIAttrGet() on the parameter descriptor returns the specific attributes of a stored procedure or function parameter, or a table column descriptor. These subsequent calls do not need an extra round-trip to the server because the entire schema object description is cached on the client side by OCIDescribeAny(). Calling OCIAttrGet() on the describe handle also returns the total number of positions.

If the OCI_ATTR_DESC_PUBLIC attribute is set on the describe handle, then the object named is looked up as a public synonym when the object does not exist in the current schema and only name1 is specified.

See Also:

Chapter 6 for more information about describe operations

OCIStmtGetBindInfo()

Purpose

Gets the bind and indicator variable names.

Syntax

sword OCIStmtGetBindInfo ( OCIStmt      *stmtp,
                           OCIError     *errhp,
                           ub4          size,
                           ub4          startloc,
                           sb4          *found,
                           OraText      *bvnp[],
                           ub1          bvnl[],
                           OraText      *invp[],
                           ub1          inpl[],
                           ub1          dupl[],
                           OCIBind      *hndl[] );

Parameters

stmtp (IN)

The statement handle prepared by OCIStmtPrepare().

errhp (IN)

An error handle that you can pass to OCIErrorGet() for diagnostic information when there is an error.

size (IN)

The number of elements in each array.

startloc (IN)

Position of the bind variable at which to start getting bind information.

found (IN)

The expression abs(found) gives the total number of bind variables in the statement irrespective of the start position. Positive value if the number of bind variables returned is less than the size provided, otherwise negative.

bvnp (OUT)

Array of pointers to hold bind variable names. Is in the encoding specified by the charset parameter of a previous call to OCIEnvNlsCreate().

bvnl (OUT)

Array to hold the length of the each bvnp element. The length is in bytes.

invp (OUT)

Array of pointers to hold indicator variable names. Must be in the encoding specified by the charset parameter of a previous call to OCIEnvNlsCreate().

inpl (OUT)

Array of pointers to hold the length of the each invp element. In number of bytes.

dupl (OUT)

An array whose element value is 0 or 1 depending on whether the bind position is a duplicate of another.

hndl (OUT)

An array that returns the bind handle if binds have been done for the bind position. No handle is returned for duplicates.

Comments

This call returns information about bind variables after a statement has been prepared. This includes bind names, indicator names, and whether binds are duplicate binds. This call also returns an associated bind handle if there is one. The call sets the found parameter to the total number of bind variables and not just the number of distinct bind variables.

OCI_NO_DATA is returned if the statement has no bind variables or if the starting bind position specified in the invocation does not exist in the statement.

This function does not include SELECT INTO list variables, because they are not considered to be binds.

The statement must have been prepared with a call to OCIStmtPrepare() prior to this call. The encoding setting in the statement handle determines whether Unicode strings are retrieved.

This call is processed locally.

Related Functions

OCIStmtPrepare()