为什么OleDbSchemaGuid不支持描述字段？

Question

为什么OleDbSchemaGuid不支持描述字段？ 在此代码中返回数据库中的所有字段，但列和表的描述始终为=“”！ 我如何从数据库中获取描述？

    Dim Schema = conn.GetOleDbSchemaTable(OleDbSchemaGuid.Columns, New Object() {Nothing, Nothing, Name, Nothing})
For i = 0 To Schema.Rows.Count - 1
   Dim culmSchema As New ColumnSchema
                    With culmSchema
                        .DatabaseName = Schema.Rows(i)!TABLE_CATALOG.ToString()
                        .Schema = Schema.Rows(i)!TABLE_SCHEMA.ToString()
                        .TableName = Schema.Rows(i)!TABLE_NAME.ToString()
                        .Name = Schema.Rows(i)!COLUMN_NAME.ToString()
                        .Description = Schema.Rows(i)!DESCRIPTION.ToString() ' Return String.Empthy Always!! 
Next i 
End With

谢谢！