Question

我正在尝试使用按钮上的以下代码运行我的系统但是我得到一个很长的错误（我要发布一个链接到屏幕截图，因为我没有足够的声誉。）谢谢！ http://i.imgur.com/MM2GP00.png 以下是代码：

Private Sub Button8_Click(sender As System.Object, e As System.EventArgs) Handles Button8.Click
        Try
            Dim sqlquery As String = "UPDATE books SET Title = @titl, Author = @aut, " & _
                         "WHERE ID = " & DataGridView2.SelectedRows(0).Cells(0).Value.ToString & ";"

            ' Use this form to initialize both connection and command to 
            ' avoid forgetting to set the appropriate properties....

            Using conn = New System.Data.OleDb.OleDbConnection(cnString)
                Using cmd = New System.Data.OleDb.OleDbCommand(sqlquery, conn)

                    conn.Open()
                    cmd.Parameters.AddWithValue("@titl", TextBox2.Text)
                    cmd.Parameters.AddWithValue("@aut", TextBox3.Text)

                    If TextBox2.Text = "" Or TextBox3.Text = "" Then
                        MessageBox.Show("Please complete the required fields.", "Admin", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
                        Return
                    Else
                        Dim rowsInserted = cmd.ExecuteNonQuery()
                        If rowsInserted > 0 Then
                            MessageBox.Show("A record has been successfully updated!", "Updated!")
                            dtgrd()
                        Else
                            MessageBox.Show("Failed to update record!", "Failure!")
                        End If
                    End If

                End Using
            End Using
        Catch ex As Exception
            MsgBox(ex.ToString)
        End Try
    End Sub

Answer 1

您的SQL查询Author = @aut,中有额外的逗号，请尝试删除

在代码中替换

Dim sqlquery As String = "UPDATE books SET Title = @titl, Author = @aut " & _
   "WHERE ID = " & DataGridView2.SelectedRows(0).Cells(0).Value.ToString & ";"

还有一件事，就是在打开连接后检查代码中的文本框空值，在执行任何操作之前尝试执行该验证。然后你的代码将是这样的

Private Sub Button8_Click(sender As System.Object, e As System.EventArgs) Handles Button8.Click
  Try          
    If TextBox2.Text = "" Or TextBox3.Text = "" Then
       MessageBox.Show("Please complete the required fields.", "Admin", MessageBoxButtons.OK, 
            MessageBoxIcon.Exclamation)
       Return
    End If

    Dim sqlquery As String = "UPDATE books SET Title = @titl, Author = @aut " & _
             "WHERE ID = " & DataGridView2.SelectedRows(0).Cells(0).Value.ToString & ";"

    ' Use this form to initialize both connection and command to 
    ' avoid forgetting to set the appropriate properties....

    Using conn = New System.Data.OleDb.OleDbConnection(cnString)
    Using cmd = New System.Data.OleDb.OleDbCommand(sqlquery, conn)

     conn.Open()
     cmd.Parameters.AddWithValue("@titl", TextBox2.Text)
     cmd.Parameters.AddWithValue("@aut", TextBox3.Text)

     Dim rowsInserted = cmd.ExecuteNonQuery()
     If rowsInserted > 0 Then
        MessageBox.Show("A record has been successfully updated!", "Updated!")
        dtgrd()
     Else
       MessageBox.Show("Failed to update record!", "Failure!")
     End If
    End Using
   End Using
   Catch ex As Exception
      MsgBox(ex.ToString)
  End Try
End Sub

更新语句错误？

1 个答案: