1. 显示某一天的 上班，下班
数据样式：
sql：
SELECT u.name,s.iname,s.CheckTime,x.iname,x.CheckTime from Users u
LEFT JOIN (SELECT UserId, CheckTime, MIN(CheckTime) mindatetime, iname FROM WX_Sign where iname = '上班' GROUP BY UserId, CheckTime, iname) s on s.userid = u.Account
left join (SELECT UserId, CheckTime, MIN(CheckTime)mindatetime, iname FROM WX_Sign where iname = '下班' GROUP BY UserId, CheckTime, iname ) x on x.userid = u.Account and
CONVERT(date, s.CheckTime)= CONVERT(date, x.CheckTime)
where s.CheckTime is not null
呈现结果：
2. 迟到，早退，人数统计
select u.Name,
sum(case when (ws.iname='上班' and convert(char(5),ws.CheckTime,108) > ws.StdTime) then 1 else 0 end) '迟到数',
sum(case when (ws.iname='下班' and convert(char(5),ws.CheckTime,108) < ws.StdTime) then 1 else 0 end) '早退数'
from WX_Sign ws
left join Users u on ws.UserId = u.Account
GROUP BY u.Name
3. 关于行转列的sql
参考网址：https://www.cnblogs.com/no27/p/6398130.html