Types of UDRs

You can write the following types of C UDRs.

Type of UDR	Description	C implementation
User-defined function	Returns one or more values and therefore can be used in SQL expressions For example, the following query returns the results of a UDR named area() as part of the query results: `SELECT diameter, area(diameter) FROM shapes WHERE diameter > 6;`	A C function that returns some data type other than void (usually a DataBlade API data type)
User-defined procedure	Does not return any values and cannot be used in SQL expressions because it does not return a value You can call a user-defined procedure directly, however, as the following example shows: `EXECUTE PROCEDURE myproc(1, 5);`	A C function that returns void