MySQL 字段分组

SELECT * FROM user GROUP BY id;

SELECT * FROM user GROUP BY 1; #列序号也可以

GROUP_CONCAT()的到分组详情

聚合函数

COUNT()

MAX()

MIN()

AVG()

SUM()

所有记录的汇总

WITH ROLLUP

例子 

SELECT age, GROUP_CONCAT(NAME), MAX(age) COUNT(*) AS total FROM user GROUP BY(age) WITHROLLUP;

注意 COUNT()不统计NULL字段