Invoking a User-Defined Routine

A UDR can be invoked either explicitly or implicitly. For more information, see Running a User-Defined Routine.

Explicit Invocation

You can use the EXECUTE PROCEDURE and EXECUTE FUNCTION statements to execute a UDR from:

• A UDR
• DB-Access
• A client application (such as an ESQL/C application)

In addition, you can use a user-defined function in an SQL expression in the SELECT clause or WHERE clause. You cannot use a procedure in an SQL expression because a procedure does not return a value.

Implicit Invocation

The database server can invoke a UDR implicitly for following reasons.

Implicit Call of UDR

UDR Called

Built-in operator binding

Operator function

Implicit casting

Implicit cast function

Opaque-type processing

Opaque-type support functions and statistics functions

Query processing

Optimization functions and operator-class functions