Using User-Defined Variables

Using User-Defined Variables

You can employ MySQL user variables to remember results without having to store them in temporary variables in the client. (See Section 8.4, “User-Defined Variables”.)

For example, to find the articles with the highest and lowest price you can do this:

mysql> SELECT @min_price:=MIN(price),@max_price:=MAX(price) FROM shop;mysql> SELECT * FROM shop WHERE price=@min_price OR price=@max_price;+---------+--------+-------+| article | dealer | price |+---------+--------+-------+|    0003 | D      |  1.25 ||    0004 | D      | 19.95 |+---------+--------+-------+

Note

It is also possible to store the name of a database object such as a table or a column in a user variable and then to use this variable in an SQL statement; however, this requires the use of a prepared statement. See Section 12.6, “SQL Syntax for Prepared Statements”, for more information.