Question

我遇到了这个问题，如果select查询有行，它会将数据传递给datagridview，但如果查询结果没有行，则会出现messagebox，其中包含＆＃34;此代码没有记录。＆＃34; < / p>

这是我的代码：

Private Sub txtScheduleID_KeyDown(sender As Object, e As KeyEventArgs) Handles txtScheduleID.KeyDown
    If (e.KeyCode = Keys.Space) Then

        Dim TextboxValue As String = RTrim(txtScheduleID.Text)
        Dim vals = TextboxValue.Split(" ").Last()

        sqlCon.Open()
        Try
            Dim QUERY As String

            QUERY = "SELECT [Class Schedule LINE].SchedID, ListofSubjects.[Course No.], ListofSubjects.[Descriptive Title], Section.Section, Curriculum.[Lab.] + Curriculum.[Lec.], UtlyTIMETable.[FROM Time] +'-'+ UtlyTIMETable.[TO Time] + '   ' + UtlyDAY.Day + '   ' + UtlyRoom.Building + ' ' +UtlyRoom.[Room No.], UtlyInstructor.[Last Name] + ', ' + LEFT (UtlyInstructor.[First Name],1)+'.' " &
                    "FROM   [Class Schedule LINE] INNER JOIN Curriculum ON [Class Schedule LINE].[Subject Code] = Curriculum.[Subject Code] INNER JOIN ListofSubjects ON Curriculum.SubjectID = ListofSubjects.SubjectID INNER JOIN Section ON [Class Schedule LINE].Section = Section.SectionID INNER JOIN UtlyTIMETable ON [Class Schedule LINE].TimeID = UtlyTIMETable.TimeID INNER JOIN UtlyDAY ON [Class Schedule LINE].DayID = UtlyDAY.DayID INNER JOIN UtlyRoom ON [Class Schedule LINE].RoomID = UtlyRoom.RoomID INNER JOIN UtlyInstructor ON [Class Schedule LINE].InstructorID = UtlyInstructor.IntructorID " &
                    "WHERE  ([Class Schedule LINE].SchedID =  '" + vals + "') "
            CMD = New SqlCommand(QUERY, sqlCon)
            Reader = CMD.ExecuteReader
            While Reader.Read
                table.Rows.Add(Reader.GetInt32(0), Reader.GetString(1), Reader.GetString(2), Reader.GetString(3), Reader.GetDecimal(4), Reader.GetString(5), Reader.GetString(6))
                dgvSubjectsEnrolled.DataSource = table
            End While
        Catch ex As Exception
            MessageBox.Show(ex.Message)
        End Try
        sqlCon.Close()
    End If
End Sub

请编辑我的代码。感谢

Answer 1

读者没有行不是错误。

If Reader.HasRows Then
 While Reader.Read
'Your code
Else
MessageBox.Show()
End If

如何放置你的连接。关闭在一个Finally块中，这样即使出现错误，你也确定它会关闭。首先检查它的状态。

如果select查询在vb.net中没有返回任何行，则显示messagebox

1 个答案: