GNU Info

(mysql.info)Adding functions

---

Next: Adding procedures Prev: Extending MySQL Up: Extending MySQL

---

Enter node , (file) or (file)node

Adding New Functions to MySQL
=============================

There are two ways to add new functions to MySQL:

   * You can add the function through the user-definable function (UDF)
     interface.  User-definable functions are added and removed
     dynamically using the `CREATE FUNCTION' and `DROP FUNCTION'
     statements.  Note: `CREATE FUNCTION'.

   * You can add the function as a native (built in) MySQL function.
     Native functions are compiled into the `mysqld' server and become
     available on a permanent basis.

Each method has advantages and disadvantages:

   * If you write a user-definable function, you must install the
     object file in addition to the server itself.  If you compile your
     function into the server, you don't need to do that.

   * You can add UDFs to a binary MySQL distribution.  Native functions
     require you to modify a source distribution.

   * If you upgrade your MySQL distribution, you can continue to use
     your previously installed UDFs.  For native functions, you must
     repeat your modifications each time you upgrade.

Whichever method you use to add new functions, they may be used just
like native functions such as `ABS()' or `SOUNDEX()'.

CREATE FUNCTION

`CREATE FUNCTION/DROP FUNCTION' Syntax

Adding UDF

Adding a new user-definable function

Adding native function

Adding a new native function