Question

mysql如何把字段做为条件放到where后面

如表1
字段a1 字段a2
1 1>0
2 2>0
3 3<4

Answer 1

如下：

select col1,sum(cols2) from table_name group by col1 having sum(col2)>100

不需要用where，用having就可以，这个就代表查询按照col1分组后，sum(col2)大于100的那些。

Answer 2

where a1 > 0 and a2 > 0 and a3 < 4