Call Level Interface Guide and Reference

Using LOBs in ODBC Applications

Existing ODBC applications use SQL_LONGVARCHAR and SQL_LONGVARBINARY instead of the DB2 BLOB and CLOB data types. By setting the LONGDATACOMPAT keyword in the initialization file, or setting the SQL_ATTR_LONGDATA_COMPAT connection attribute using SQLSetConnectAttr(), DB2 CLI will map the ODBC long data types to the DB2 LOB data types.

When this mapping is in effect:

• SQLGetTypeInfo() will return CLOB, BLOB and DBCLOB characteristics when called with SQL_LONGVARCHAR, SQL_LONGVARBINARY or SQL_LONGVARGRAPHIC.

• The following functions will return SQL_LONGVARCHAR, SQL_LONGVARBINARY or SQL_LONGVARGRAPHIC when describing CLOB, BLOB or DBCLOB data types:
  • SQLColumns()
  • SQLSpecialColumns()
  • SQLDescribeCol()
  • SQLColAttribute()
  • SQLProcedureColumns()

• LONG VARCHAR and LONG VARCHAR FOR BIT DATA will continue to be described as SQL_LONGVARCHAR and SQL_LONGVARBINARY.

The default setting for SQL_ATTR_LONGDATA_COMPAT is SQL_LD_COMPAT_NO, mapping is not in effect.

For more information, refer to "Configuration Keywords", and SQLSetConnectAttr - Set Connection Attributes.

With the mapping in effect, ODBC applications can retrieve LOB data by using the SQLGetData(), SQLPutData() and related functions. For more information about inserting and retrieving data in pieces, refer to "Sending/Retrieving Long Data in Pieces".

Note:

DB2 CLI uses a temporary file when inserting LOB data in pieces. If the data originates in a file, the use of a temporary file can be avoided by using SQLBindFileToParam(). Call SQLGetFunctions() to query if support is provided for SQLBindFileToParam().

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