SQL Server 2008列表項不在表中

Question

一個簡單的查詢，應該查看systemSoftware表和軟件表，並只顯示softwareId不在systemSoftware表內。

這裏是我的查詢到目前爲止...

SELECT s.softwareId AS 'Software ID', 
    s.softwareDescription AS 'Software Description', 
    sv.vendorName AS 'Vendor Name', 
    c.cityName AS 'City Name' 
FROM software AS s 
JOIN systemSoftware AS ss 
ON s.softwareId = ss.softwareId 
JOIN softwareVendor AS sv 
ON s.vendorId = sv.vendorId 
JOIN city AS c 
ON sv.zipCode = c.zipCode 
WHERE s.softwareId NOT IN (ss.softwareId) 
ORDER BY s.softwareId 
GO 

當我刪除了不就顯示所有softwareId行均在systemSoftware。

問題是我想要相反。那些不在systemSoftware。

Answer 1

你需要一個左外連接：

SELECT ss.softwareId AS 'Software ID', 
    s.softwareDescription AS 'Software Description', 
    sv.vendorName AS 'Vendor Name', 
    c.cityName AS 'City Name' 
FROM software AS s 
left outer JOIN systemSoftware AS ss 
ON s.softwareId = ss.softwareId 
left outer JOIN softwareVendor AS sv 
ON s.vendorId = sv.vendorId 
left outer JOIN city AS c 
ON sv.zipCode = c.zipCode 
WHERE ss.softwareId is NULL 
ORDER BY s.softwareId 

我也改變了ORDER BY，因爲它沒有任何意義的一列中不存在訂購。