mysql - 如果没有找到记录如何显示消息

Question

这是我将数据过滤到文本框/标签中的代码

Dim reader As MySqlDataReader
    Try
        If conn.State = ConnectionState.Closed Then
            conn.Open()
        End If

        Dim query As String
        query = "SELECT * FROM member WHERE (memor = '" & memor.Text & "')"

        sqlcom = New MySqlCommand(query, conn)
        reader = sqlcom.ExecuteReader
        While reader.Read()
            Me.lblname.Text = reader("membname").ToString
            Me.txtmembtype.Text = reader("membtype").ToString
            Me.lblmembdate.Text = reader("membdate").ToString
        End While

        conn.Close()
    Catch ex As Exception
        MessageBox.Show(ex.Message)
    Finally
        conn.Dispose()
    End Try

现在我想要一个消息框，提示我的mysql数据库中没有找到数据？有什么想法吗？

Answer 1

您可以简单地使用reader.HasRows()来检查记录

reader = sqlcom.ExecuteReader
if Reader.HasRows() Then
    While reader.Read()
        Me.lblname.Text = reader("membname").ToString
        Me.txtmembtype.Text = reader("membtype").ToString
        Me.lblmembdate.Text = reader("membdate").ToString
    End While
Else
    MessageBox.Show("No records found")
End If