SQL SELECT JOIN

Question

员工登录表

Employeeno  | day_in  | day_out 
| 2017-06-20 | 2017-06-21 
| 2017-06-21 | 2017-06-22 
0122    | 2017-06-20 | 2017-06-21 
0122    | 2017-06-22 | 2017-06-23 
0121    | 2017-06-23 | 2017-06-24 

我想查询不到2017年6月21日的员工谁拥有day_in（日期时间）和天大于2017年6月21日这是员工编号0122。

Answer 1

只需使用子查询来获得结果。

SELECT Employeeno FROM [Employee_logs] where day_in<' 2017-06-21' and Employeeno in(
    SELECT Employeeno FROM [Employee_logs] where day_in>' 2017-06-21') 

Answer 2

创建表脚本

Create table Attendance(Employeeno int ,day_in datetime,day_out datetime) 

插入记录脚本

Insert into Attendance 
    Select 0123,'2017-06-20 ','2017-06-21' union 
    Select 0123,'2017-06-21 ','2017-06-22' union 
    Select 0122,'2017-06-20 ','2017-06-21' union 
    Select 0122,'2017-06-22 ','2017-06-23' union 
    Select 0121,'2017-06-23 ','2017-06-24' 

方法1

SELECT Employeeno FROM Attendance where day_in<' 2017-06-21' INTERSECT 
SELECT Employeeno FROM Attendance where day_in>' 2017-06-21' 

对于我上面的方法我都用过INTERSECT这给普通的记录。 全部使用可以蜜蜂在这里看到[https://blog.sqlauthority.com/2008/10/17/sql-server-get-common-records-from-two-tables-without-using-join/]

方法2

WITH x AS 
(
    -- Gives the result for Employees with Days_in less 2017-06-21 
    SELECT * FROM Attendance where day_in<'2017-06-21' 
), 
y AS 
(
     -- Gives the result for Employees with Days_in greater than 2017-06-21 
    SELECT * FROM Attendance where day_in>'2017-06-21' 
) 
SELECT * FROM y join x on y.Employeeno=x.Employeeno 
-- Give the result based on the required query for all employees. 

Answer 3

如果使用派生表找到的最早和最晚day-in值，你可以很容易地找到那些符合条件的：

-- Create test data 
declare @t table(Employeeno nvarchar(5), day_in date, day_out date); 
insert into @t values 
('0123','2017-06-20','2017-06-21') 
,('0123','2017-06-21','2017-06-22') 
,('0122','2017-06-20','2017-06-21') 
,('0122','2017-06-22','2017-06-23') 
,('0121','2017-06-23','2017-06-24'); 

-- Query 
with d as 
(
    select Employeeno 
      ,min(day_in) as EarliestDayIn 
      ,max(day_in) as LatestDayIn 
    from @t 
    group by Employeeno 
) 
select * 
from d 
where EarliestDayIn < '20170621' 
    and LatestDayIn > '20170621'; 

输出：

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