MYSQL随机从表中取指定数量的数据

列如从student表中随机取num个人数

SELECT * FROM student ORDER BY RAND() LIMIT 0,num;//俩个语句效果相同
SELECT * FROM student ORDER BY RAND() LIMIT num;

列如从student表中随机取性别为男的num个人数

SELECT * FROM student WHERE sex = "男" ORDER BY RAND() LIMIT 0,num;//俩个语句效果相同
SELECT * FROM student WHERE sex = "男" ORDER BY RAND() LIMIT num;