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.
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