由多個刪除行加入

Question

我想通過參加多個表刪除行，你可以看到，但它引發我一個錯誤：

DELETE FROM Reg INNER JOIN 
      RegDoc ON Reg.RegId = RegDoc.RegId INNER JOIN 
      Doc ON RegDoc.DocId = Doc.DocId 
WHERE Doc.Name LIKE N'%Title%' 

收到錯誤：

Msg 156, Level 15, State 1, Line 1 Incorrect syntax near the keyword 'INNER'.

Answer 1

的正確的語法是

DELETE [ FROM ] { <object> } 
[ FROM <table_source>] 
[ WHERE { <search_condition> } ] 

應用您的例子，這會成爲

DELETE FROM Reg 
FROM Reg 
     INNER JOIN RegDoc ON Reg.RegId = RegDoc.RegId 
     INNER JOIN Doc ON RegDoc.DocId = Doc.DocId 
WHERE Doc.Name LIKE N'%Title%' 

注引用到Reg表

這可以通過混疊（雖然有在這種情況下沒有必要），進一步縮短

DELETE FROM r 
FROM Reg r 
     INNER JOIN RegDoc ON r.RegId = RegDoc.RegId 
     INNER JOIN Doc ON RegDoc.DocId = Doc.DocId 
WHERE Doc.Name LIKE N'%Title%' 

---

MSDN例

DELETE FROM Sales.SalesPersonQuotaHistory 
FROM Sales.SalesPersonQuotaHistory AS spqh 
INNER JOIN Sales.SalesPerson AS sp 
ON spqh.BusinessEntityID = sp.BusinessEntityID 
WHERE sp.SalesYTD > 2500000.00; 

Answer 2

使用此

DELETE 
FROM Reg 
FROM Reg 
INNER JOIN 
      RegDoc ON Reg.RegId = RegDoc.RegId INNER JOIN 
      Doc ON RegDoc.DocId = Doc.DocId 
WHERE Doc.Name LIKE N'%Title%' 

或更清晰，恕我直言：

DELETE Reg 
FROM Reg 
INNER JOIN RegDoc 
    ON Reg.RegId = RegDoc.RegId 
INNER JOIN Doc 
    ON RegDoc.DocId = Doc.DocId 
WHERE Doc.Name LIKE N'%Title%' 

Answer 3

你可以這樣說：

DELETE Reg 
FROM Reg 
INNER JOIN RegDoc ON Reg.RegId = RegDoc.RegId 
INNER JOIN Doc ON RegDoc.DocId = Doc.DocId 
WHERE Doc.Name LIKE N'%Title%' 

Answer 4

您可以使用一個別名，

DELETE r 
FROM Reg as r 
INNER JOIN RegDoc rd ON r.RegId = rd.RegId 
INNER JOIN Doc d ON rd.DocId = d.DocId 

實際上，你可以delete rd和delete d太：雖然它，如果你使用的別名是從表的名稱不同更清晰。

Answer 5

略高於其他答案不同的方法（這都是很好的）

DELETE FROM Reg 
WHERE Reg.RegID IN (SELECT RegDoc.RegId 
        FROM RegDoc 
         INNER JOIN Doc 
         ON RegDoc.DocId = Doc.DocId 
        WHERE Doc.Name LIKE N'%Title%')