Some Open Client and Open Server datatypes do not directly map to target datatypes. For example, Open Client and Open Server CS_DATETIME and CS_DATETIME4 datatypes do not directly map to DB2 DATE, TIME, or TIMESTAMP datatypes.
When defaults are not appropriate for these datatype conversions, the CT-Library client can specify the intended DB2 datatype by using the usertype field in the parameter’s CS_DATAFMT structure. The client fills in the CS_DATAFMT structure and a pointer to the structure is passed to the ct_param Open Client function call.
Then, the DB2 access service converts the Open Client and Open Server datatype to the precise target datatype.
DB-Library clients cannot take advantage of this feature and are limited to the default datatype conversions.
