Functional types of routines

There are different functional types of routines. Each functional type provides support for invoking routines from different interfaces for different purposes. Each functional type of routine provides a different set of features and SQL support.

Procedures, also called stored procedures, serve as sub-routine extensions to client applications, routines, triggers, and dynamic compound statements. Procedures are invoked by executing the CALL statement with a reference to a procedure. Procedures can have input, output, and input-output parameters, can execute a wide variety of SQL statements, and return multiple result sets to the caller.
Functions are relationships between sets of input data values and a set of result values. Functions enable you to extend and customize SQL. Functions are invoked from within elements of SQL statements such as a select-list, expression, or a FROM clause. There are four types of functions: aggregate functions, scalar functions, row functions, and table functions.
Methods allow you to access user-defined type attributes as well as to define additional behaviors for user-defined types. A structured type is a user-defined data type containing one or more named attributes, each of which has a data type. Attributes are properties that describe an instance of a type. A geometric shape, for example, might have attributes such as its list of Cartesian coordinates. A method is generally implemented for a structured type as an operation on the attributes of the structured type. For a geometric shape a method might calculate the volume of the shape.

For specific details on each of the functional routine types refer to the topics for each routine type.