select
count(*) as mcount ,
left(create_time,10) as ptime ,
count(if(receive_msg is null,id,null)) as nullcount ,
count(if(receive_msg = '1',receive_msg,null)) as apfcount ,
count(if(receive_msg = '2',receive_msg,null)) as dttcount ,
count(if(receive_msg = '3',receive_msg,null)) as dicount
from
t_votes
where
left(create_time,7)>='$pearly'
and
left(create_time,7)<='$plate'
group by
ptime ;
COUNT(*)带上值为NULL的
COUNT(table_name)不带值为NULL的
计数不求和,可用其他字段替代
select
count(*) as mcount ,
left(create_time,10) as ptime ,
SUM(if(receive_msg is null,id,0)) as nullcount ,
SUM(if(receive_msg = '1',receive_msg,0)) as apfcount ,
SUM(if(receive_msg = '2',receive_msg,0)) as dttcount ,
SUM(if(receive_msg = '3',receive_msg,0)) as dicount
from
t_votes
where
left(create_time,7)>='$pearly'
and
left(create_time,7)<='$plate'
group by
ptime ;
SUM求和,最后一个参数改为0.具体原因不明
今天，用Navicat为两张表建立外健关系，总是提示创建失败信息，发现是两张表关联的字段类型问题，但两个字段都是int型哩，怎么会还会类型不一致呢，最后发现到一个地方有点不一样，就是在“设计表”界面下方有个“无符号”的复选框，两张表的主键字段其中一个没勾选上这个复选框而导致虽然都是int类型� ......
