删除记录时如何重置表的标识列？

Question

我有一个Datagridview，它从SQL Server中填充了一些数据。这没关系，没问题。

每次我在表中插入或更新记录时，我想重新设置一个名为IDENTITY的CarID列，但IDS序列似乎不好，因为有时会删除记录。

在我的代码中，我使用'SQLCOMMANDBUILDER'来执行插入，更新或删除操作。

我尝试了下面的代码但是我抛出一个异常错误，上面写着“找不到表0”。

我应该在哪里修理？

//THESE ARE CODE TO RESEED AN IDENTITY COLUMN

Sub ResetIDColumn()
    Try
        Dim querystring As String = "declare @max int " &
                        "Select @max=max([CarID]) FROM [dbo].[Cars]" &
                        "if @max IS NULL SET @max = 0 " &
                        "DBCC CHECKIDENT ('[Cars]', RESEED,@max)"
        ds = New DataSet
        da = New SqlDataAdapter(querystring, con)
        cmdbuilder = New SqlCommandBuilder(da)
        da.Fill(ds)
        DgvCarList.DataSource = ds.Tables(0)

    Catch ex As Exception
        MessageBox.Show(ex.Message)
    End Try
End Sub

 //CODE TO PUPOLATE DATAGRIDVIEW
Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) 
Handles MyBase.Load
    Try
        Dim querystring As String = "SELECT * FROM [dbo].[Cars]"
        ds = New DataSet
        da = New SqlDataAdapter(querystring, con)
        cmdbuilder = New SqlCommandBuilder(da)
        da.Fill(ds)
        DgvCarList.DataSource = ds.Tables(0)

    Catch ex As Exception
        MessageBox.Show(ex.Message)
    End Try
End Sub

//CODE TO INSERT OR UPDATE DATA

Private Sub btnUpdate_Click(sender As System.Object, e As System.EventArgs) Handles btnUpdate.Click
    ResetIDColumn()
    Try
        da.Update(ds.Tables(0))
        MessageBox.Show("Update was successful!", "Data")
        Loaddata()
    Catch ex As Exception
        MessageBox.Show(ex.Message)
    End Try
End Sub

//CODE TO LOAD DATA 
Sub Loaddata()
    Dim querystring As String = "SELECT * FROM [dbo].[Cars]"
    ds = New DataSet
    da = New SqlDataAdapter(querystring, con)
    cmdbuilder = New SqlCommandBuilder(da)
    da.Fill(ds)
    DgvCarList.DataSource = ds.Tables(0)
    DgvCarList.AutoSizeColumnsMode = DataGridViewAutoSizeColumnsMode.Fill
End Sub

Answer 1

我越来越努力，终于发现了 - ;

1. 您需要创建一个新的数据集，Sqlcommandbuilder和new dataadapter然后查询 来自您的表的数据（使用select语句）同时执行命令以使用'single querystring'重置id。
2. 执行两个命令的目的是使所有结果存储在SINGLE DATASET中
3. 我决定在从表中删除记录后调用此子。

码：

// Button click to delete a record
 Try
        If ds.Tables(0).Rows.Count > 0 Then
            Dim rowposition As Integer = DgvCarList.CurrentRow.Index
            Dim rowdelete As DataRow = ds.Tables(0).Rows(rowposition)
            rowdelete.Delete()
            da.Update(ds)
            MessageBox.Show("Delete was success!", "Data")
            Loaddata()
        End If
    Catch ex As Exception
        MessageBox.Show(ex.Message)
    End Try

  // After delete completed Go and reset an identity column 
    ResetIDColumn()


  // code to reset an identity column
 Sub ResetIDColumn()
    Try
        Dim querystring As String = "SELECT * FROM [dbo].[Cars] go " &
                                     "DECLARE @max INT " &
                        "Select @max=max([CarID]) FROM [dbo].[Cars]" &
                        "if @max IS NULL SET @max = 0 " &
                        "DBCC CHECKIDENT ('[Cars]', RESEED,@max)"
        ds = New DataSet
        da = New SqlDataAdapter(querystring, con)
        cmdbuilder = New SqlCommandBuilder(da)
        da.Fill(ds)
        DgvCarList.DataSource = ds.Tables(0)

    Catch ex As Exception
        MessageBox.Show(ex.Message)
    End Try
End Sub


          ...................Thank you all..................................