1

当我运行此代码时，它还会检索表中不存在的其他一些字段。我该如何克服呢？

Dim conn As New OleDb.OleDbConnection
'Create a connection string for an Access database
Dim strConnectionString = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=F:\check\a.mdb"
'Attach the connection string to the connection object
conn.ConnectionString = strConnectionString
'Open the connection
conn.Open()
Dim Restrictions() As String = {Nothing, Nothing, selected, Nothing}
Dim CollectionName As String = "Columns"
Dim dt As DataTable = conn.GetSchema(CollectionName, Restrictions)
For Each TableRow As DataRow In dt.Rows
    ComboBox1.Items.Add(TableRow.Item("COLUMN_NAME"))

还检索到的其他列是：

1.ID
2.日期创建3.日期
更新
4.Id
5.Lv
6.Name
7.parent Id
8.Type
9.GUID
10.Id

...还有 6 个。原始模式仅包含 5 个字段。

4

2 回答 2

1

您的问题只是当您将变量插入数组时它selected具有该值。当我运行以下代码时，我只获得名为 [new] 的表的列名：NothingRestrictions()

Option Strict On

Imports System.Data.OleDb

Module Module1

    Sub Main()
        Dim connStr As String =
                "Provider=Microsoft.ACE.OLEDB.12.0;" &
                "Data Source=C:\Users\Public\test\so34490626\a.mdb"
        Using conn As New OleDbConnection(connStr)
            conn.Open()
            Dim selected As String = "new"
            Dim Restrictions() As String = {Nothing, Nothing, selected, Nothing}
            Dim CollectionName As String = "Columns"
            Dim dt As DataTable = conn.GetSchema(CollectionName, Restrictions)
            For Each TableRow As DataRow In dt.Rows
                Console.WriteLine(TableRow.Item("COLUMN_NAME"))
            Next
        End Using
    End Sub

End Module

结果是：

GENDER
MEMBER OF RISHI PRASAD
NAME OF SADHAK
PROFESSION

但是，当 的selected值为Nothing...

Dim selected As String = Nothing

...我得到你描述的“额外”列

DateCreate
DateUpdate
Id
Lv
Name
ParentId
Type
Attributes
DataType
FieldName
IndexType
SkipColumn
SpecID
Start
Width
DateDelim
DateFourDigitYear
DateLeadingZeros
DateOrder
DecimalPoint
FieldSeparator
FileType
SpecID
SpecName
SpecType
StartRow
TextDelim
TimeDelim
GENDER
MEMBER OF RISHI PRASAD
NAME OF SADHAK
PROFESSION

Console.WriteLine如果我将其更改为包含表名，则会显示原因：

Console.WriteLine("[{0}].[{1}]", TableRow.Item("TABLE_NAME"), TableRow.Item("COLUMN_NAME"))

然后我们看到：

[MSysAccessStorage].[DateCreate]
[MSysAccessStorage].[DateUpdate]
[MSysAccessStorage].[Id]
[MSysAccessStorage].[Lv]
[MSysAccessStorage].[Name]
[MSysAccessStorage].[ParentId]
[MSysAccessStorage].[Type]
[MSysIMEXColumns].[Attributes]
[MSysIMEXColumns].[DataType]
[MSysIMEXColumns].[FieldName]
[MSysIMEXColumns].[IndexType]
[MSysIMEXColumns].[SkipColumn]
[MSysIMEXColumns].[SpecID]
[MSysIMEXColumns].[Start]
[MSysIMEXColumns].[Width]
[MSysIMEXSpecs].[DateDelim]
[MSysIMEXSpecs].[DateFourDigitYear]
[MSysIMEXSpecs].[DateLeadingZeros]
[MSysIMEXSpecs].[DateOrder]
[MSysIMEXSpecs].[DecimalPoint]
[MSysIMEXSpecs].[FieldSeparator]
[MSysIMEXSpecs].[FileType]
[MSysIMEXSpecs].[SpecID]
[MSysIMEXSpecs].[SpecName]
[MSysIMEXSpecs].[SpecType]
[MSysIMEXSpecs].[StartRow]
[MSysIMEXSpecs].[TextDelim]
[MSysIMEXSpecs].[TimeDelim]
[new].[GENDER]
[new].[MEMBER OF RISHI PRASAD]
[new].[NAME OF SADHAK]
[new].[PROFESSION]

“MSys*”表是默认隐藏在 Access 用户界面中的系统表。

于 2015-12-31T03:02:33.227 回答
0

在循环您的表行之前，您需要识别数据表的有效/永久列。

为此，您应该首先浏览数据表对象的列集合。通过检查每一列的属性，您将能够识别临时列。我猜它可能隐藏在 DataColumn 对象的“扩展属性”中的某个地方。

为了确定正确的属性，您将经历这样的事情（即时编写......）：

For each tableColumn as DataColumn in dt.Columns
    Console.WriteLine(tableColumn.[propertyName].ToString())
    ...
Next

我不确切知道哪个属性会让您知道该列是否是原始表字段的一部分。您必须猜测和测试才能找到它。一旦确定，您就知道如何选择要添加到组合框中的行。

于 2015-12-28T09:28:34.453 回答