MySQL运算符

比较运算符

LEAST

SELECT LEAST(2, 0); => 0
SELECT LEAST(20.0, 3.0, 100.5); => 3.0
SELECT LEAST('a', 'b', 'c'); => a
SELECT LEAST(5, NULL); => NULL

GREATEST

SELECT GREATEST(2, 0); => 2
SELECT GREATEST(20.0, 3.0, 100.5); => 100.5
SELECT GREATEST('a', 'b', 'c'); => c
SELECT GREATEST(5, NULL); => NULL

IN / NOT IN

SELECT 1 IN (1, 2, 3); => 1
SELECT 1 IN (1, 2, 3, NULL); => 1
SELECT NULL IN (1, 2, 3, NULL); => NULL
SELECT 1 NOT IN (1, 2, 3); => 0

LIKE

• %：匹配任何数目的字符，甚至包括零字符。
• _：只能匹配一个字符。

SELECT 'ABC' LIKE '%BC%'; => 1
SELECT 'ABC' LIKE '%BC_'; => 0
SELECT 'ABC' LIKE NULL; => NULL