For....Next 语句

Dim tablename As String = "couset"
            searchSQL = "select * from couset　where zy='" & ComboBox1.Text & "'"
            ExecuteSQL(searchSQL, tablename)
            Dim newrow As DataRow
            newrow = mytable.NewRow
            Dim sql As String
            Dim i As Int16
            For i = 1 To .........???
                newrow.Item(1) = Trim(ComboBox1.Text)
                newrow.Item(2) = Trim(ListBox2.Items.Item(i))
                mytable.Rows.Add(newrow)
            Next
怎么在这里得到记录的总数？？
是不是要用sql语句得到？？
怎么写？？
谢谢！！