vb.net - 数据表不知道其主键

Question

我正在尝试通过查询每个列的自动增量属性来查询数据表以建立主键[标识列]。但是它始终为 false(对于 Idenity/PK 列)。

查询表主键集合显示数据表不认为它具有 PK。;

  Dim dc As DataColumn() = dt.PrimaryKey
  Debug.WriteLine(dc.Count)  'Result is 0

正在填充数据表......

Using cn As SqlConnection = MyApp.GetConnection
  Using cmd As New SqlCommand(strSQL, cn)
    Using da As New SqlDataAdapter(cmd)
      Dim ds As New DataSet
      Try
        da.Fill(ds)

        Return ds

      Catch ex As Exception
        MyAppClass.LogWarning(ex, EventLogEntryType.Error)
        Throw
      End Try
    End Using 
  End Using 
End Using

相关表的主键是:([myTableId] [int] IDENTITY(1,1) NOT NULL)。及其 pk :约束 [PK_myTablesPK] 主键聚集 ( [myTableId] ASC )

这里有人遇到了同样的问题(也许比我写的更清楚):http://social.msdn.microsoft.com/Forums/en-US/adodotnetdataproviders/thread/c6abdeef-0cb0-42f5-a5f1-10dc4d81df4a/

我假设我缺少一些简单的东西，有人愿意启发我吗？

Answer 1

使用 fillschema 解决了我的问题；

da.FillSchema(ds, SchemaType.Mapped, table.tableName)
da.Fill(ds, table.tableName)

The DataAdapter object is optimized for read-only scenarios by default. The Fill method only retrieves the amount of schema that is necessary to populate a DataSet object. To obtain the additional schema that are necessary to update or validate DataSet objects, use one of the following methods for DataSet objects that are populated by the DataAdapater:

• Use the FillSchema method of the DataAdapter.
• Use the AddWithKey enumeration for the MissingSchemaAction property of the DataAdapter.

This article describes how to choose between these two methods when you want to populate updateable DataSet objects with the DataAdapter.

REF : http://support.microsoft.com/kb/310128