java - 如何编写Mysql查询以根据日期从数据库中获取数据？

Question

我的数据库表是::

attendence date     admission number         attendence

  2013-10-2         LSTM-0008/2013-2014      present

 2013-10-19         LSTM-0008/2013-2014      absent

  2013-10-20         LSTM-0008/2013-2014      present

上面一个是我的数据库表。

我想在这里显示这样的表 totalworkingdays 是基于数据库表的那个月的存在和缺席总数:

 MonthName     totalWorkingDays     Present     absent

 october            3                  2          1

我这样写 mysql 查询:

select distinct
    monthname(attendencedate) as monthname,
    count(*) as totalworkingdays
from  lstms_attendence where
    attendencedate> '2013-10-01' and attendencedate<'2013-10-31'
    and addmissionno='LSTM-0008/2013-2014'
GROUP BY
    monthname(attendencedate),
    sum(CASE WHEN attendence = 'present' THEN 1 ELSE 0 END) as present,
    SUM(CASE WHEN attendence = 'absent' THEN 1 ELSE 0 END) AS absent
FROM lstms_attendence
WHERE addmissionno = 'LSTM-0008/2013-2014'
GROUP BY monthname(attendencedate);

我得到了这样的错误::

错误代码:1064 您的 SQL 语法有误；检查与您的 MySQL 服务器版本相对应的手册，了解在第 1 行使用 near 'as present,SUM(CASE WHEN attendence = 'absent' THEN 1 ELSE 0 END) AS absent FRO' 的正确语法 (用了 0 毫秒)

任何人都给我建议。提前致谢。

Answer 1

请记住始终以更易读的方式放置查询。

滚动的需要令人厌恶。

有点乱

几个 FROM 和 GROUP BY 子句...

应该看起来更像

SELECT DISTINCT
    monthname(attendencedate) as monthname,
    count(*) as totalworkingdays,
    sum(CASE WHEN attendence = 'present' THEN 1 ELSE 0 END) as present,
    SUM(CASE WHEN attendence = 'absent' THEN 1 ELSE 0 END) AS absent
FROM  lstms_attendence
WHERE
    attendencedate> '2013-10-01' and attendencedate<'2013-10-31'
    and addmissionno='LSTM-0008/2013-2014'
GROUP BY
    monthname(attendencedate)

AFAIR 你不能将 AS 放在 GROUP BY 子句中。这就是 MySQL 告诉你的。

附言。未测试