访问：如何在整个数据库中查找字段？

Question

我有一个包含许多表的访问数据库。我正在寻找一个可能存在也可能不存在于一个或多个表中的字段。如何检查它是否存在？ （当然不用查询每张表）

Answer 1

字段有一个模式：

Set cn = CurrentProject.Connection

SelectFieldName = "SomeFieldName" 

'Get names of all tables that have a column = SelectFieldName '
Set rs = cn.OpenSchema(adSchemaColumns, _
Array(Empty, Empty, Empty, SelectFieldName))

发件人：MS Access: How to bypass/suppress an error?

Answer 2

如果您真的不想打开任何表，一个解决方案是使用数据库对象的tabledefs 集合。每个tabledef 项目都有自己的fields 集合供您浏览。它会给出这样的结果：

Public function findFieldInDatabase(p_myFieldName)
    dim db as database, _
        tb as tabledef, _
        fd as field

    set db = currentDb
    for each tb in db.tabledefs
        for each fd in tb.fields
            if fd.name = p_myFieldName then
                debug.print tb.name, fd.name
            end if
        next fd
    next tb
    set fd = nothing
    set tb = nothing
    set db = nothing
end function 

这个代码可以很容易地接受一个可选的p_myTableName作为参数来限制搜索到一个表/表范围。

Answer 3

如果我想查看特定表中的特定列（在 strSearch 中标识）是否存在，我会这样做。

Public Sub search()

Dim db As Database
Dim strSearch As String
Dim strSQL As String
Dim rsResults As Recordset
Dim i As Integer
Dim cols As Integer

    strSearch = "a3"

    Set db = CurrentDb
    strSQL = "select * from bar"
    Set rsResults = db.OpenRecordset(strSQL, dbOpenDynaset, dbReadOnly)
    If Not rsResults.BOF Then
        rsResults.MoveFirst
    End If

    cols = rsResults.Fields.Count - 1 ' -1 because we start counting cols at 0
    For i = 0 To cols
        If rsResults(i).Name = strSearch Then
            MsgBox "Found the seach string"
        End If
    Next
    MsgBox "end of script"

End Sub

现在我知道你不想为每张桌子写一个。所以接下来要做的就是遍历所有的表。您可以使用以下 SQL 找到所有表的列表

SELECT 
    name
FROM 
    MSysObjects 
WHERE 
    (Left([Name],1)<>"~") 
    AND (Left([Name],4) <> "MSys") 
    AND ([Type] In (1, 4, 6)) 

将这两部分连接在一起，我将留给学生作为练习:)

Answer 4

以下是在 MS Access 中使用 VBScript 访问表架构的方法：

TestData = "PROVIDER=Microsoft.Jet.OLEDB.4.0;Data Source=c:\somefolder\YOURDB.mdb"
Set Conn = Server.CreateObject("ADODB.Connection")
Conn.Open TestData

Set rs = Conn.OpenSchema(4)

do until Rs.eof
    tn = RS("TABLE_NAME")
    fn = RS("COLUMN_NAME")
    ' your script goes here
loop

Answer 5

给你：

Public Function fTableExists(ByVal vstrTable As String) As Boolean
    Dim rs As ADODB.Recordset
    Set rs = CurrentProject.Connection.OpenSchema( _
           adschematables, Array(Empty, Empty, vstrTable))
    fTableExists = Not rs.EOF
    rs.Close
    Set rs = Nothing
End Function

Public Function fColumnExists(ByVal vstrTable As String, _
                              ByVal vstrColumn As String) As Boolean
    Dim rs As ADODB.Recordset
    Set rs = CurrentProject.Connection.OpenSchema(adSchemaColumns, _
      Array(Empty, Empty, vstrTable, vstrColumn))
    fColumnExists = Not rs.EOF
    rs.Close
    Set rs = Nothing
End Function

Answer 6

MSSQL 寻找 ADDRESS1 列： 从 sysobjects 中选择 so.name 所以 where so.id in (select sc.id from syscolumns sc where name like 'ADDRESS1')

甲骨文 http://en.wikipedia.org/wiki/Oracle_metadata

Google 会找到其他数据库的语法...

Answer 7

它是什么类型的数据库？如果是 SQL Server，你可以试试这个：

SELECT * FROM sysobjects WHERE xtype = 'U' AND name = 'myTable'

但由于它是您要查找的列而不是表（感谢 Brian），请尝试以下操作：

SELECT 
    DISTINCT
    so.[name] AS 'Table',
    sc.[name] AS 'Column' 
    FROM 
        syscolumns sc
    JOIN
        sysobjects so
        ON
            so.id = sc.id
    WHERE 
        sc.[name] = 'myTable'