Large object and user-defined data type mapping
HCL Informix® OLE DB
Provider supports
large objects and user-defined data types as follows:
- The BYTE data type is reported by IColumnsInfo::GetColumnInfo() and appropriate schema rowsets as DBTYPE_BYTES; the TEXT data type is reported as DBTYPE_STR. Values of BYTE and TEXT types are cached in memory.
- Complex data types are reported by IColumnsInfo::GetColumnInfo() and
appropriate schema rowsets as DBTYPE_VARIANT. The corresponding value
is a safe array.
This mapping is known to work with ADO and Visual Basic/VBScript.
- The CLOB data type is reported by IColumnsInfo::GetColumnInfo() and
appropriate schema rowsets as DBTYPE_STR with the IS_LONG flag set;
the BLOB data type is reported as DBTYPE_BYTES with the IS_LONG flag
set.
This mapping allows ADO to open storage objects on smart large object data and manipulate it with the GetChunk() and AppendChunk() methods.
- Distinct data types are generally resolved to their source type. For example, if you define an HTML type as a distinct CLOB data type, IColumnsInfo::GetColumnInfo() and appropriate schema rowsets report it as DBTYPE_STR with the IS_LONG flag set.
- Opaque data types are reported by IColumnsInfo::GetColumnInfo() and appropriate schema rowsets as DBTYPE_BYTES.