Save 和 Open 方法范例 (VB)

这三个范例演示如何配合使用 Save 和 Open 方法。

假设用户在出差时需要携带数据库中的一个表。在出发前，用户以 Recordset 访问数据，并将其保存为便携格式。在到达目的地后，用户以本地、断开连接的方式访问 Recordset，在修改 Recordset 后将其保存。最后，当用户回家后，再次连接数据库并用旅途中所做的更改对其进行更新。

Public Sub Main()
    SaveX1
    SaveX2
    SaveX3
End Sub

首先，访问并保存 Authors 表。

Public Sub SaveX1()
Dim rst As ADODB.Recordset
Set rst = New ADODB.Recordset

rst.Open "SELECT au_id, au_lname, au_fname, phone FROM Authors", _
         "Provider=SQLOLEDB;Data Source=MySrvr;User Id=uid;" & _
         "Password=pwd;Initial Catalog=pubs;" _
         adOpenDynamic, adLockOptimistic, adCmdText

'For sake of illustration, save the Recordset to a diskette in XML
'format.
rst.Save "a:Pubs.xml", adPersistXML

rst.Close
End Sub

现在用户已到达目的地。以本地、断开连接的 Recordset 访问 Authors 表。请注意，要访问保存的文件 a:Pubs.xml，必须在用户使用的机器上装有 MSPersist 提供者。

Public Sub SaveX2()
Dim rst As ADODB.Recordset
Set rst = New ADODB.Recordset

'For sake of illustration, we specify all parameters.
rst.Open "a:Pubs.xml", "Provider=MSPersist;", , , adCmdFile

'Now you have a local, disconnected Recordset. Edit it as you desire.
'(In this example, the change makes no difference).
rst.Find "au_lname = 'Carson'"
If rst.EOF Then
    Debug.Print "Name not found."
    Exit Sub
End If

rst!city = "Berkeley"
rst.Update

'Save changes in ADTG format this time, purely for sake of illustration.
'Note that the previous version is still on the diskette, as a:Pubs.xml.
rst.Save "a:Pubs.adtg", adPersistADTG
rst.Close
End Sub

最后用户回到家里。现在用所做的更改更新数据库。

Public Sub SaveX3()
Dim cnn As New ADODB.Connection
Dim rst As ADODB.Recordset
Set rst = New ADODB.Recordset

'If there is no ActiveConnection, you can open with defaults.
rst.Open "a:Pubs.adtg"

'Connect to the database, associate the Recordset with the connection,
'then update the database table with the changed Recordset.
cnn.Open "Provider=SQLOLEDB;Data Source=MySrvr;User Id=uid;" & _
         "Password=pwd;Initial Catalog=pubs;"
rst.ActiveConnection = cnn
rst.UpdateBatch

rst.Close
cnn.Close
End Sub