Syntax
------

SET var_name = expr [, var_name = expr] ...

Description
-----------

The SET statement in stored programs is an extended version of the general SET
statement. Referenced variables may be ones declared inside a stored program,
global system variables, or user-defined variables.

The SET statement in stored programs is implemented as part of the
pre-existing SET syntax. This allows an extended syntax of SET a=x, b=y, ...
where different variable types (locally declared variables, global and session
server variables, user-defined variables) can be mixed. This also allows
combinations of local variables and some options that make sense only for
system variables; in that case, the options are recognized but ignored.

SET can be used with both local variables and user-defined variables.

When setting several variables using the columns returned by a query, SELECT
INTO should be preferred.

To set many variables to the same value, the LAST_VALUE( ) function can be
used.

Below is an example of how a user-defined variable may be set:

SET @x = 1;

URL: https://mariadb.com/kb/en/set-variable/