http://dev.mysql.com/doc/refman/5.0/en/comparison-operators.html

BETWEEN … AND … Check whether a value is within a range of values
COALESCE() Return the first non-NULL argument
<=> NULL-safe equal to operator
= Equal operator
>= Greater than or equal operator
> Greater than operator
GREATEST() Return the largest argument
IN() Check whether a value is within a set of values
INTERVAL() Return the index of the argument that is less than the first argument
IS NOT NULL NOT NULL value test
IS NOT Test a value against a boolean
IS NULL NULL value test
IS Test a value against a boolean
ISNULL() Test whether the argument is NULL
LEAST() Return the smallest argument
<= Less than or equal operator
< Less than operator
LIKE Simple pattern matching
NOT BETWEEN … AND … Check whether a value is not within a range of values
!=, <> Not equal operator
NOT IN() Check whether a value is not within a set of values
NOT LIKE Negation of simple pattern matching
SOUNDS LIKE(v4.1.0) Compare sounds