MySQueaL Resources

SET Statement

This MySQL statement sets a system or user variable for global or session use.

This MySQL statement sets a system or user variable for global or session use. Global variables relate to all users. Session variables are available only to the MySQL connection thread that creates the variable. For system variables to be recognized as global, the GLOBAL keyword is used. Alternatively, the variable can be preceded by @@global. to signify that it is global. For system variables that are limited to the current session, use the SESSION keyword, or place @@session or just @@ immediately in front of the variable name. The default for variables is to limit them to the session, making them local. LOCAL and @@local are aliases for SESSION and @@session, respectively.

Here are a couple of examples of this MySQL statement involving system variables, one using the keyword method and the other using the variable prefix method:

SET GLOBAL concurrent_insert =  1;
SET @@session.interactive_timeout=40000;

The first statement disables concurrent inserts without having to restart the server. The second statement changes the interactive timeout to a higher value than normal. This setting is for the current client connection to MySQL only. For other MySQL clients, this variable will still contain the default value.

To see a list of system variables and their values, use the SHOW VARIABLES statement. For examples involving user variables, see the other documentation page on SET.