主题：遍历数据源某表所有列时 如何返回列的长度

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MaxLength

这个代码  用在外部表的 时候  返回的值 全是 -1   下面是代码

Dim x As String = MainTable.name
Dim x1 As String
Dim lst As List(Of String)
st = Connections("服务器").GetTableNames
For Each nm As String In lst
    'x1 = x1 & "|" & nm
Next

If x1 Like "'*" & x & "*'" Then
    Dim cmd As New SQLCommand
    Dim dt As DataTable
    cmd.C
    cmd.CommandText = "SELECT * From {" & x & "}"
    dt = cmd.ExecuteReader()   
    For Each cl As DataCol In dt.DataCols
        Dim dr As DataRow = DataTables("GJ动态建表_临时").AddNew()
        dr("列名")  = cl.name
        dr("数据源类型") = cl.DataType.name
        dr("长度") =cl.MaxLength
    Next
'End If