38.4. User-defined Procedures
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A procedure is a database object similar to a function. The difference is that a procedure does not return a value, so there is no return type declaration. While a function is called as part of a query or DML command, a procedure is called explicitly using the statement.
The explanations on how to define user-defined functions in the rest of this chapter apply to procedures as well, except that the command is used instead, there is no return type, and some other features such as strictness don't apply.
Collectively, functions and procedures are also known as routines. There are commands such as and that can operate on functions and procedures without having to know which kind it is. Note, however, that there is no CREATE ROUTINE command.