DataColumn的AutoIncrement总是返回False

Question

我有兴趣查看列是否具有自动递增/allowdbnull属性。

下面有这段代码，虽然我已经有了一个具有自动增量/allowdbnull属性的列，但它总是给出了false。

Dim dt As New DataTable()
Dim con As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source =" &             Application.StartupPath & "\test.mdb"
Dim sql As String = "SELECT * from teachers"
Dim i As Integer



Dim dataAdapter As New OleDb.OleDbDataAdapter(sql, con)
dataAdapter.Fill(dt)
dataAdapter.Dispose()



For Each column As DataColumn In dt.Columns

TextBox1.Text = TextBox1.Text & column.ColumnName & "      " & column.AutoIncrement & "        " & column.AllowDBNull & vbCrLf

Next

谢谢。

Answer 1

要使代码正常工作，只需添加(在调用Fill方法之前)

  dataAdapter.MissingSchemaAction = MissingSchemaAction.AddWithKey

这将迫使适配器检索有关主键和自动编号字段的信息。

MSDN MissingSchemaAction enumeration

Answer 2

ds = new dataset()

dataAdapter.Fill(ds,0,1,"Teachers")

dataAdapter.FillSchema(ds, SchemaType.Source, "Teachers");

dt = ds.tables(0)