Question

以下SQL语句在我的数据库上执行正常：

SELECT * FROM tblKPIs AS k 
INNER JOIN tblKeyPointLinks AS l ON k.KPIID = l.KPIID 
INNER JOIN tblKeyPoints AS p ON p.KptID = l.KptID 
INNER JOIN tblHistory AS h ON h.HistoryID = p.HistoryID 
WHERE h.CaseNo = 50043;

然而，等效的Delete语句会在AS附近出现错误'语法？

DELETE FROM tblKPIs AS k 
INNER JOIN tblKeyPointLinks AS l ON k.KPIID = l.KPIID 
INNER JOIN tblKeyPoints AS p ON p.KptID = l.KptID 
INNER JOIN tblHistory AS h ON h.HistoryID = p.HistoryID 
WHERE h.CaseNo = 50043;

我可以在删除语句中使用联接吗？

如果不能如何执行上述删除？

修改

表tblKeyPointLinks是一个中间表，用于在tblKPI和tblKeyPoints之间建立多对多关系。因此，SELECT语句会多次返回tblKPI中的一些条目。这是为什么DELETE语句可能有问题？解决这个问题的最佳方法是什么？

Answer 1

是的，您可以加入删除声明：

DELETE k FROM tblKPIs AS k 
INNER JOIN tblKeyPointLinks AS l ON k.KPIID = l.KPIID 
INNER JOIN tblKeyPoints AS p ON p.KptID = l.KptID 
INNER JOIN tblHistory AS h ON h.HistoryID = p.HistoryID 
WHERE h.CaseNo = 50043;

Answer 2

你可以这样做：

DELETE FROM tblKPIs 
  WHERE id in (
    SELECT id 
      FROM tblKPIs AS k 
      INNER JOIN tblKeyPointLinks AS l ON k.KPIID = l.KPIID 
      INNER JOIN tblKeyPoints AS p ON p.KptID = l.KptID 
      INNER JOIN tblHistory AS h ON h.HistoryID = p.HistoryID 
      WHERE h.CaseNo = 50043)

Answer 3

成功的代码如下：

DELETE k
FROM tblKPIs k  
     INNER JOIN tblKeyPointLinks l ON k.KPIID = l.KPIID
     INNER JOIN tblKeyPoints p ON p.KptID = l.KptID
     INNER JOIN tblHistory h ON h.HistoryID = p.HistoryID
WHERE h.CaseNo = 50043;

显然DELETE语句不喜欢使用关键字AS 只需省略AS关键字，该语句就可以正常工作。

使用内部联接删除TSQL

3 个答案: