如何从已存在于另一个TABLE中的TABLE中删除数据 [英] How can I delete data from a TABLE that's already exists in another TABLE

问题描述

我正在使用visual studio 2017和ms access for Windows表单应用程序。我有一个会员和一个支持者表。这两个表都有一个coloumn [AADHAAR]。在两个表中，[AADHAAR]是主要的。如果在MEMBERS表的[AADHAAR]列中找到匹配项，我想删除SUPPORTERS表中的所有记录。



我使用了一个执行任务的按钮。



注意：MEMBERS表的[AADHAAR]列和SUPPORTERS表的[AADHAAR]列之间有10个以上的匹配项。仍然ExecuteNonQuery（）返回0.所以不发布评论，如没有匹配。 bla ... bla .. bla ..



我尝试过：

I am using visual studio 2017 and ms access 2016 for a Windows forms application. I have a MEMBERS and a SUPPORTERS table. Both of the table has a coloumn [AADHAAR]. In both tables the [AADHAAR] is primary. I want to delete all the records from SUPPORTERS table if a match found with [AADHAAR] column of MEMBERS table.

I have used a button which does the task..

Note: There are more than 10 matches between [AADHAAR] column of MEMBERS table and [AADHAAR] column of SUPPORTERS table. Still ExecuteNonQuery() returns 0. So dont post comments like there is no matches. bla.. bla.. bla..

What I have tried:

private Sub Extra_Btn_Click(sender As Object, e As EventArgs) Handles Extra_Btn.Click
       If Merge_Data() = True Then
           MsgBox("Duplicate Data removed")
       Else
           MsgBox("Error! ")
       End If
   End Sub

函数Merge_Data的定义：

Definition of The function Merge_Data :

Public Function Merge_Data() As Boolean
        Try
            Link()
            cmd.CommandText = "DELETE * FROM SUPPORTERS WHERE SUPPORTERS.AADHAAR IN (SELECT MEMBERS.AADHAAR FROM MEMBERS)"
            Records = cmd.ExecuteNonQuery()
        Catch ex As Exception
            MsgBox(ex.Message)
        End Try

        If Records > 0 Then
            Return True
        Else
            Return False
        End If

    End Function

这不会工作。只显示Msgbox（错误！）意味着ExecuteNonQuery（）返回0。因此，Merge_Data（）返回False

This Doesnt Work.Simply Msgbox("Error! ") appears that means ExecuteNonQuery() retuns 0 . Hence Merge_Data() returns False

推荐答案

从查询中删除*

Remove * from Query

DELETE FROM SUPPORTERS WHERE SUPPORTERS.AADHAAR IN (SELECT MEMBERS.AADHAAR FROM  MEMBERS )

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