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MySQL 9.0 supports stored routines written in JavaScript, as in the simple example shown here:

mysql> CREATE FUNCTION add_nos(arg1 INT, arg2 INT)     ->   RETURNS INT LANGUAGE JAVASCRIPT AS     ->   $$    $>     return arg1 + arg2    $>   $$    ->   ;Query OK, 0 rows affected (0.01 sec)mysql> SELECT add_nos(12,52);+----------------+| add_nos(12,52) |+----------------+|             64 |+----------------+1 row in set (0.00 sec)

JavaScript stored programs can be used together with other user-created and MySQL-native stored programs (subject to limitations described elsewhere in this section), as well as with MySQL system and user variables. We can see some of this here, using theadd_nos() function created in the previous example:

mysql> SET @x = 2;Query OK, 0 rows affected (0.00 sec)mysql> SELECT @x;+------+| @x   |+------+|    2 |+------+1 row in set (0.00 sec)mysql> SELECT @@server_id;+-------------+| @@server_id |+-------------+|           1 |+-------------+1 row in set (0.00 sec)mysql> SELECT add_nos(POW(2,@x), 1);+-----------------------+| add_nos(POW(2,@x), 1) |+-----------------------+|                     5 |+-----------------------+1 row in set (0.01 sec)mysql> SELECT POW(add_nos(@x, @@server_id), add_nos(@x, 1));+-----------------------------------------------+| POW(add_nos(@x, @@server_id), add_nos(@x, 1)) |+-----------------------------------------------+|                                            27 |+-----------------------------------------------+1 row in set (0.01 sec)

JavaScript stored procedures can be invoked usingCALL, as with SQL stored procedures.

JavaScript stored programs can also take column values as arguments. JavaScript stored functions can be invoked anywhere in an SQL expression that it is legal to use any other function, such as inWHERE,HAVING,ORDER BY, andJOIN clauses. They can also be invoked within the body of a trigger or event definition, although the definitions themselves must be written in SQL. Examples of some of these features can be found later in this section (seeSection 27.3.9, “JavaScript Stored Program Examples”).