SQLGetSubString - Retrieve portion of a string value

SQLGetSubString() is used to retrieve a portion of a large object value referenced by a large object locator. The large object locator has been returned from the data source (returned by a fetch or a previous SQLGetSubString() call) during the current transaction.

Unicode (UTF-16) equivalent: This function can also be used with the Unicode (UTF-16) character set. The corresponding Unicode function is SQLGetSubStringW(). Refer to Unicode in Db2 for i CLI for more information about Unicode support for DB2® CLI.

Syntax

SQLRETURN  SQLGetSubString   (
                SQLHSTMT          StatementHandle,
                SQLSMALLINT       LocatorCType,
                SQLINTEGER        SourceLocator,
                SQLINTEGER        FromPosition,
                SQLINTEGER        ForLength,
                SQLSMALLINT       TargetCType,
                SQLPOINTER        DataPtr, 
                SQLINTEGER        BufferLength,
                SQLINTEGER        *StringLength,
                SQLINTEGER        *IndicatorValue);

Function arguments

Table 1. SQLGetSubString arguments
Data type Argument Use Description
SQLHSTMT StatementHandle input Statement handle. This can be any statement handle which has been allocated but which does not currently have a prepared statement assigned to it.
SQLSMALLINT LocatorCType input The C type of the source LOB locator. This can be:
  • SQL_C_BLOB_LOCATOR
  • SQL_C_CLOB_LOCATOR
  • SQL_C_DBCLOB_LOCATOR
SQLINTEGER SourceLocator input SourceLocator must be set to the source LOB locator value.
SQLINTEGER FromPosition input For BLOBs and CLOBs, this is the position of the first byte to be returned by the function. For DBCLOBs, this is the first character. The start byte or character is numbered 1.
SQLINTEGER ForLength input This is the length of the string to be returned by the function. For BLOBs and CLOBs, this is the length in bytes. For DBCLOBs, this is the length in characters.

If FromPosition is less than the length of the source string but FromPosition + ForLength - 1 extends beyond the end of the source string, the result is padded on the right with the necessary number of characters (X'00' for BLOBs, single byte blank character for CLOBs, and double byte blank character for DBCLOBs).
SQLSMALLINT TargetCType input The C data type of the DataPtr. The target must be a C string variable (SQL_C_CHAR, SQL_C_WCHAR, SQL_C_BINARY, or SQL_C_DBCHAR).
SQLPOINTER DataPtr output Pointer to the buffer where the retrieved string value or a LOB locator is to be stored.
SQLINTEGER BufferLength input Maximum size of the buffer pointed to by DataPtr in bytes.
SQLINTEGER * StringLength output The length of the returned information in DataPtr in bytesa if the target C buffer type is intended for a binary or character string variable and not a locator value.

If the pointer is set to NULL, nothing is returned.
SQLINTEGER * IndicatorValue output Always set to zero.
Note: 1. This is in bytes even for DBCLOB data.

Usage

SQLGetSubString() is used to obtain any portion of the string that is represented by the LOB locator. There are two choices for the target:
  • The target can be an appropriate C string variable.
  • A new LOB value can be created on the server and the LOB locator for that value can be assigned to a target application variable on the client.

SQLGetSubString() can be used as an alternative to SQLGetData() for getting data in pieces. In this case a column is first bound to a LOB locator, which is then used to fetch the LOB as a whole or in pieces.

The Locator argument can contain any valid LOB locator which has not been explicitly freed using a FREE LOCATOR statement nor implicitly freed because the transaction during which it is created has terminated.

The statement handle must not have been associated with any prepared statements or catalog function calls.

If a locator entry exists in the locator table but has no data, SQLGetSubString() will return an SQL_NO_DATA return code.

If a remote connection has been made, the CCSID of the CLOB data (SourceLocator) must be compatible with the CCSID of the job executing the SQLGetSubString API, otherwise translation problems will occur.

Return codes

  • SQL_SUCCESS
  • SQL_SUCCESS_WITH_INFO
  • SQL_ERROR
  • SQL_INVALID_HANDLE
  • SQL_NO_DATA

Error conditions

Table 2. SQLGetSubString SQLSTATEs
SQLSTATE Description Explanation
01004 Data truncated The amount of data to be returned is longer than BufferLength. Actual length available for return is stored in StringLength.
07006 Conversion that is not valid The value specified for TargetCType is not SQL_C_CHAR, SQL_C_BINARY, SQL_C_DBCHAR, or a LOB locator.

The value specified for TargetCType is inappropriate for the source (for example SQL_C_DBCHAR for a BLOB column).
22011 Substring error occurred FromPosition is greater than the length of the source string.
58004 Unexpected system failure Unrecoverable system error.
HY003 Program type out of range LocatorCType is not one of SQL_C_CLOB_LOCATOR, SQL_C_BLOB_LOCATOR, or SQL_C_DBCLOB_LOCATOR.
HY009 Argument value that is not valid The value specified for FromPosition or ForLength is not a positive integer.

The argument DataPtr, StringLength, or IndicatorValue is a null pointer
HY010 Function sequence error The specified StatementHandle is not in an allocated state.
HY021 Internal descriptor that is not valid The internal descriptor cannot be addressed or allocated, or it contains a value that is not valid.
HY090 String or buffer length that is not valid The value of BufferLength is less than 0.
HYC00 Driver not capable The application is currently connected to a data source that does not support large objects.
0F001 No locator currently assigned The value specified for Locator is not currently a LOB locator.

Restrictions

This function is not available when connected to a DB2 server that does not support Large Objects.

References