-
时间类
select now();
select curdate();
select curtime();
select day(last_day(now())); # last day
select date_add('2018-09-2', interval 1 day);
select date_add('2018-09-2', interval '2 01:30:19' day_second); # 加
select date_sub('1998-01-01', interval '1 1:1:1' day_second); # 减日期
select datediff('2018-02-11', '2019-9-11'); # 日期相减
select timediff('2018-02-11', '2019-9-11');
-
字符串处理
select length(' s 2 b '); # 计算长度
select concat('2222', '2232', '423'); # 拼接
select concat_ws('**', '2232', '423'); # 指定拼接符
select format(1223523.236, 2); # 122,3523.24
select lower('ASDFSDF');
SELECT upper('aaaa');
select replace(' sss ss ', ' ',''); # 替换
-
聚合函数
AVG(DISTINCT age) # distinct 去重
1. AVG
2. COUNT
3. MIX/MAX
4. SUM
-
流程控制函数 # todo
case if ifnull nullif
select ifnull(1/0, 'xxx'); # 有为空选项
