mysql - 如何使用vb.net和mysql获得最大值

Question

我在 mysql 中有一个包含数据的列 (copy_no1)

301
67
1234
2345
3433-a
6543
456
2344

此数据中 --- 最大的数字是 --- 6543如何从vb.net代码中获取它？

我的代码是----

Dim cmd As MySqlCommand
        Dim rs As MySqlDataReader
        cmd = con.CreateCommand
        'cmd.CommandText = "select MAX(won) from field_copy_no"
        cmd.CommandText = "select * from field_copy_no order by copy_no1"
        rs = cmd.ExecuteReader
        While rs.Read

            Label9.Text = rs.GetString(3)
            Label10.Text = rs.GetString(4)
        End While
        rs.Close()
        cmd.Dispose()

通过使用这两个命令文本，我得到了结果 - 67

Answer 1

为什么不直接使用 MAX() 函数？

    Dim cmd As MySqlCommand
    Dim rs As MySqlDataReader
    cmd = con.CreateCommand
    cmd.CommandText = "select max(CAST(copy_no1 as UNSIGNED)) as value from field_copy_no"
    rs = cmd.ExecuteReader
    If rs.Read
        Label9.Text = rs.GetString(0)
    End While
    rs.Close()
    cmd.Dispose()