Open Client user-defined datatypes

An application that needs to use a datatype that is not included in the standard Open Client type set may create a user-defined datatype.

A Client-Library application creates a user-defined type by declaring it:

typedef char    CODE_NAME;

The Open Client routines ct_bind and cs_set_convert use integer symbolic constants to identify datatypes, so it is often convenient for an application to declare a type constant for a user-defined type. User-defined types must be defined as greater than or equal to CS_USERTYPE:

#define CODE_NAME_TYPE    (CS_USERTYPE + 2)

Once a user-defined type has been created, an application:

After conversion routines are installed, an application binds server results to a user-defined type:

mydatafmt.datatype = CODE_NAME_TYPE;
 ct_bind(cmd, 1, &mydatafmt, mycodename, NULL,
     NULL);

Custom conversion routines are called transparently, whenever required, by ct_fetch (following a call to ct_bind specifying the conversion) and cs_convert.

NoteDo not confuse Open Client user-defined types with Adaptive Server user-defined types. Open Client user-defined types are C-language types, declared within an application. Adaptive Server user-defined types are database column datatypes, created using the system stored procedure sp_addtype.