如何在DATAGRIDVIEW中显示冲突而不是MsgBox

Question

请为我的论文提供帮助。我正在为注册系统创建一个计划。我正在使用Table“classsubjects”进行测试。

这是我的示例代码。

    Try
        con.Open()
        cmd.Connection = con
        cmd.CommandType = CommandType.Text
        cmd.CommandText = String.Format("SELECT * " & _
                             "FROM classsubjects " & _
                             "WHERE subject_code='{0}' " & _
                             "AND subject_name='{1}' " & _
                             "AND year_level='{2}' ", subjcode.Text, subjname.Text, subjyearlevel.Text)
        dr = cmd.ExecuteReader

        If dr.HasRows Then
            'MsgBox("Conflict Found, please check !", MsgBoxStyle.Critical)
            DataGridView1.Rows.Add("subject_ID,subject_code,subject_name,year_level", subjID.Text, subjcode.Text, subjname.Text, subjyearlevel.Text) '

            con.Close()
        Else
            con.Close()
            con.Open()
            cmd.Connection = con
            cmd.CommandType = CommandType.Text
            cmd.CommandText = "INSERT into classsubjects(subject_ID, subject_code, subject_name, year_level)VALUES('" + subjID.Text + "','" + subjcode.Text + "','" + subjname.Text + "','" + subjyearlevel.Text + "')"
            cmd.ExecuteNonQuery()
            MsgBox("Successfully Saved")
        End If
    Catch ex As Exception
        MessageBox.Show(ex.Message)
    Finally
        con.Close()
    End Try