SQL-PL allows the effects of SQL statements to be extended by user-specific DB functions. Thus more applications logic can be shifted to the database server.
DB functions are defined in the programming language . They can be used like predefined functions in the SELECT list of a command, in the WHERE qualification or within the SET clause of the UPDATE statement.
DB functions are specialized procedures that have any number of input parameters but only one output parameter. The output parameter represents the result of the function, thus defining the data type of the function's result.
SQL statements are not allowed within DB functions. It must be ensured that no name of a predefined function is used when naming a DB function.