sql

select student_id,avg(number)
from `score`
group by student_id
having avg(number)>60

 

为表添加索引

（foreign key (team_id) references t_team(id) ）；

 

mysql 时间格式 

date_format(add_time,'%Y-%m-%d %H:%i:%s') as addtime 时分秒显示

 

设置mysql连接数量

show variables like 'max_connections';

set GLOBAL max_connections=10000000;