分组问题！

Question

msgID     from    to        title    content          readed    type
1 michael admin  hello how are you? 0 0
2 michael admin  hello how are you? 0 0
3 michael admin  hello how are you? 1 0
4 michael admin  hello how are you? 0 0
5 michael cloudchen  hello how are you? 0 0
6 michael cloudchen  hello how are you? 0 0
7 michael cloudchen  hello how are you? 0 0
8 michael cloudchen  hello how are you? 0 0

Answer 1

把这里是字符字段的数据长度变得小一点:msgID,from,to,title,content,readed,type
比如:varchar(100)的改为varchar(50)只要没有截断数据就行如果导出到文本,把自动换行去掉

Answer 2

SELECT COUNT(msgID) count([to]),readed FROM game_msg group by readed

Answer 3

SELECT sum(case when readed=1 then 1 end) readed为1的数量,sum(case when readed=0 then 1 end) readed为0的数量  FROM game_msg