Question

我正在处理一个SQL查询，其中数据存储在表r.中基于give或receive的列，我需要将数据存储在临时表中然后存储在新表中。

本质上，数据是从3个表中提取的，最终目标是获取图像的二进制代码并存储以显示在.net

我正在尝试找出多重选择

因此give中的receive或r等于Username中的S，如果employee，则显示所有相关数据并获取图像等于employee

我已经尝试了很多代码，并且觉得OR可以解决问题，但似乎没有。

感谢您提供的任何帮助。

SELECT  
    r.id, r.give, r.[receive], r.[type], r.[description], r.isApproved, 
    r.photoGive, r.photoReceive 
INTO
    #temp2 
FROM 
    Intranet.dbo.Recgonize r

SELECT s.Employee, s.Username 
INTO #temp3 
FROM Vision7.dbo.SEUser s

SELECT p.Photo, p.Employee 
INTO #temp4 
FROM Vision7.dbo.EMPhoto p

SELECT * 
FROM #temp2 AS a
INNER JOIN #temp3 b ON a.give = b.Username 
INNER JOIN #temp4 c ON b.Employee = c.Employee

DROP TABLE #temp2
DROP TABLE #temp3
DROP TABLE #temp4

Answer 1

您可能需要尝试以下操作：

-- Include only required columns select rather than "*"

SELECT * 
FROM #temp2 AS a
INNER JOIN #temp3 b ON a.give = b.Username 
INNER JOIN #temp3 b2 ON a.receive = b2.Username 
INNER JOIN #temp4 c ON b.Employee = c.Employee
INNER JOIN #temp4 c2 ON b2.Employee = c2.Employee

或

-- Include only required columns in select rather than "*"

SELECT * 
FROM 
        (select r.id, r.give as UserName, r.[type], r.[description], r.isApproved, r.photoGive  from #temp2
         union
         select r.id, r.[receive], r.[type], r.[description], r.isApproved, r.photoReceive from #temp2
        ) AS a
INNER JOIN #temp3 b ON a.UserName = b.Username 
INNER JOIN #temp4 c ON b.Employee = c.Employee

如果临时表未用于应用程序的必要需求，则相同的逻辑可以与实际表一起使用，只需将＃Temp2，＃Temp3，＃Temp4替换为适当的表名即可。

Answer 2

尝试使用以下单个脚本-

SELECT a.id, 
       a.give, 
       a.[receive], 
       a.[type], 
       a.[description], 
       a.isApproved, 
       a.photoGive, 
       a.photoReceive, 
       b.Employee, 
       b.Username, 
       c.Photo, 
       c.Employee
FROM Intranet.dbo.Recgonize A
     INNER JOIN Vision7.dbo.SEUser B ON a.give = b.Username
     INNER JOIN Vision7.dbo.EMPhoto C ON b.Employee = c.Employee;

Answer 3

为什么要为此使用临时表？这些只会使代码更难调试和维护，运行起来更加昂贵，并且理解起来也更加复杂。

JOIN可以在没有临时表的情况下使用。但是，您确实需要附加的逻辑才能在不同的列中获取赋予和接收的值，因此需要更多JOIN：

SELECT r.id, r.give, r.[receive], r.[type], r.[description], 
       r.isApproved, r.photoGive, r.photoReceive,
       pg.Photo as give_photo, pg.Employee as give_employee,
       pr.Photo as receive_photo, pr.Employee as receive_employee
FROM Intranet.dbo.Recognize r LEFT JOIN
     Vision7.dbo.SEUser sg
     ON r.give = sg.Username LEFT JOIN
     Vision7.dbo.SEUser sr
     ON r.receive = sr.Username LEFT JOIN
     Vision7.dbo.EMPhoto pg
     ON sg.Employee = pg.Employee LEFT JOIN
     Vision7.dbo.EMPhoto pr
     ON sr.Employee = pr.Employee

SQL查询从1个表中选择并基于2列返回数据

3 个答案: