MySQL Reference Manual

Functions for Use in SELECT and WHERE Clauses

A select_expression or where_definition in a SQL statement can consist of any expression using the functions described next.

An expression that contains NULL always produces a NULL value unless otherwise indicated in the documentation for the operators and functions involved in the expression.

Note: there must be no whitespace between a function name and the parentheses following it. This helps the MySQL parser distinguish between function calls and references to tables or columns that happen to have the same name as a function. Spaces around arguments are permitted, though.

You can force MySQL to accept spaces after the function name by starting mysqld with --ansi or using the CLIENT_IGNORE_SPACE to mysql_connect( ), but in this case all function names will become reserved words. See Section 1.7.2.

For the sake of brevity, examples display the output from the mysql program in abbreviated form. So this:

mysql> SELECT MOD(29,9);
1 rows in set (0.00 sec)

+-----------+
| mod(29,9) |
+-----------+
|         2 |
+-----------+

is displayed like this:

mysql> SELECT MOD(29,9);
        -> 2

Non-Type-Specific Operators and Functions

Parentheses

( ... )

Use parentheses to force the order of evaluation in an expression. For example:

mysql> SELECT 1+2*3;
        -> 7
mysql> SELECT (1+2)*3;
        -> 9

Comparison operators

Comparison operations result in a value of 1 (TRUE), 0 (FALSE), or NULL. These functions work for both numbers and strings. Strings are automatically converted to numbers ...