循环访问 MS Access 中所有记录的代码

Question

我需要一个代码来循环遍历表中的所有记录，以便提取一些数据。除此之外，是否还可以遍历过滤记录​​并再次提取数据？谢谢！

Answer 1

您应该能够使用非常标准的 DAO 记录集循环来执行此操作。您可以在以下链接中查看一些示例：
http://msdn.microsoft.com/en-us/library/bb243789%28v=office.12%29.aspx
http://www.granite.ab.ca/access/email/recordsetloop.htm

我自己的标准循环看起来像这样：

Dim rs As DAO.Recordset
Set rs = CurrentDb.OpenRecordset("SELECT * FROM Contacts")

'Check to see if the recordset actually contains rows
If Not (rs.EOF And rs.BOF) Then
    rs.MoveFirst 'Unnecessary in this case, but still a good habit
    Do Until rs.EOF = True
        'Perform an edit
        rs.Edit
        rs!VendorYN = True
        rs("VendorYN") = True 'The other way to refer to a field
        rs.Update

        'Save contact name into a variable
        sContactName = rs!FirstName & " " & rs!LastName

        'Move to the next record. Don't ever forget to do this.
        rs.MoveNext
    Loop
Else
    MsgBox "There are no records in the recordset."
End If

MsgBox "Finished looping through records."

rs.Close 'Close the recordset
Set rs = Nothing 'Clean up

Answer 2

在“引用”中，导入 DAO 3.6 对象引用。

private sub showTableData

dim db as dao.database
dim rs as dao.recordset

set db = currentDb
set rs = db.OpenRecordSet("myTable") 'myTable is a MS-Access table created previously

'populate the table
rs.movelast
rs.movefirst

do while not rs.EOF
   debug.print(rs!myField) 'myField is a field name in table myTable
   rs.movenext             'press Ctrl+G to see debuG window beneath
loop

msgbox("End of Table")

end sub

您可以通过不同方式交互查询和过滤表等数据对象：

通过查询：

private sub showQueryData

dim db as dao.database
dim rs as dao.recordset
dim sqlStr as string

sqlStr = "SELECT * FROM customers as c WHERE c.country='Brazil'"

set db = currentDb
set rs = db.openRecordset(sqlStr)

rs.movefirst

do while not rs.EOF
  debug.print("cust ID: " & rs!id & " cust name: " & rs!name)
  rs.movenext
loop

msgbox("End of customers from Brazil")

end sub

您还应该寻找记录集对象的“过滤器”属性以仅过滤所需的记录，然后以相同的方式与它们交互（参见 MS-Access 代码窗口中的 VB6 帮助），或创建一个“QueryDef”对象运行查询并将其也用作记录集（有点棘手）。如果你想要另一种方法，请告诉我。

我希望我有所帮助。

Answer 3

找到了一个用 cmets 解释每个语句的好代码。 代码位于 -accessallinone

Sub DAOLooping()
On Error GoTo ErrorHandler

Dim strSQL As String
Dim rs As DAO.Recordset

strSQL = "tblTeachers"
'For the purposes of this post, we are simply going to make 
'strSQL equal to tblTeachers.
'You could use a full SELECT statement such as:
'SELECT * FROM tblTeachers (this would produce the same result in fact).
'You could also add a Where clause to filter which records are returned:
'SELECT * FROM tblTeachers Where ZIPPostal = '98052'
' (this would return 5 records)

Set rs = CurrentDb.OpenRecordset(strSQL)
'This line of code instantiates the recordset object!!! 
'In English, this means that we have opened up a recordset 
'and can access its values using the rs variable.

With rs


    If Not .BOF And Not .EOF Then
    'We don’t know if the recordset has any records, 
    'so we use this line of code to check. If there are no records 
    'we won’t execute any code in the if..end if statement.    

        .MoveLast
        .MoveFirst
        'It is not necessary to move to the last record and then back 
        'to the first one but it is good practice to do so.

        While (Not .EOF)
        'With this code, we are using a while loop to loop 
        'through the records. If we reach the end of the recordset, .EOF 
        'will return true and we will exit the while loop.

            Debug.Print rs.Fields("teacherID") & " " & rs.Fields("FirstName")
            'prints info from fields to the immediate window

            .MoveNext
            'We need to ensure that we use .MoveNext, 
            'otherwise we will be stuck in a loop forever… 
            '(or at least until you press CTRL+Break)
        Wend

    End If

    .close
    'Make sure you close the recordset...
End With

ExitSub:
    Set rs = Nothing
    '..and set it to nothing
    Exit Sub
ErrorHandler:
    Resume ExitSub
End Sub

记录集在循环数据时有两个重要的属性，EOF（文件结束）和 BOF（文件开始）。记录集就像表格，当您遍历一个表格时，您实际上是按顺序从一个记录移动到另一个记录。在您浏览记录时，EOF 属性设置为 false，但在您尝试越过最后一条记录后，EOF 属性变为 true。对于 BOF 属性，这同样适用。

这些属性让我们知道何时达到记录集的限制。