Choose function parameters
The following table summarizes the SQL data types for
the parameter list and return type of CREATE FUNCTION statements that
register support functions.
| Support function | Parameter type | Return type | Refer to |
|---|---|---|---|
| input | lvarchar | opaque data type | Input support function |
| output | opaque data type | lvarchar | Output support function |
| receive | sendrecv | opaque data type | The send and receive support functions |
| send | opaque data type | sendrecv | The send and receive support functions |
| import | impexp | opaque data type | Import and export support functions |
| export | opaque data type | impexp | Import and export support functions |
| importbinary | impexPbin | opaque data type | Importbinary and exportbinary support functions |
| exportbinary | opaque data type | impexpbin | Importbinary and exportbinary support functions |
| assign | opaque data type | opaque data type | The assign() function |
| destroy | opaque data type | - no return value - | The destroy() function |
| update | opaque data type, opaque data type | opaque data type | The update() function |
| deepcopy | opaque data type | The deepcopy() function | |
| lohandles | opaque data type | - list of pointers - | Handle smart large objects |
| compare | user-defined type, user-defined type | - integer values to show less than, greater than and equal - | Compare data |
In the preceding table, opaque data type is the name of the data type that you specify in the CREATE OPAQUE TYPE statement. For more information, see Register the opaque data type.
When the CREATE FUNCTION statement stores a new support function in sysprocedures, it causes the database server to assign a unique value, called a routine identifier, to the support function. Throughout the system catalog a support function is identified by its routine identifier, not by its name.