=

Syntax

left_expr = right_expr

Description

Equal operator. Evaluates both SQL expressions and returns 1 if they are equal, 0 if they are not equal, or NULL if either expression is NULL. If the expressions return different data types (for example, a number and a string), a type conversion is performed.

When used in row comparisons these two queries are synonymous and return the same results:

SELECT (t1.a, t1.b) = (t2.x, t2.y) FROM t1 INNER JOIN t2;  SELECT (t1.a = t2.x) AND (t1.b = t2.y) FROM t1 INNER JOIN t2;

To perform a NULL-safe comparison, use the <=> operator.

= can also be used as an assignment operator.

Examples

SELECT 1 = 0; +-------+ | 1 = 0 | +-------+ | 0 | +-------+  SELECT '0' = 0; +---------+ | '0' = 0 | +---------+ | 1 | +---------+  SELECT '0.0' = 0; +-----------+ | '0.0' = 0 | +-----------+ | 1 | +-----------+  SELECT '0.01' = 0; +------------+ | '0.01' = 0 | +------------+ | 0 | +------------+  SELECT '.01' = 0.01; +--------------+ | '.01' = 0.01 | +--------------+ | 1 | +--------------+  SELECT (5 * 2) = CONCAT('1', '0'); +----------------------------+ | (5 * 2) = CONCAT('1', '0') | +----------------------------+ | 1 | +----------------------------+  SELECT 1 = NULL; +----------+ | 1 = NULL | +----------+ | NULL | +----------+  SELECT NULL = NULL; +-------------+ | NULL = NULL | +-------------+ | NULL | +-------------+

See Also

• Operator Precedence

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