如何以编程方式创建到SQL Server视图的ODBC链接表并使其可编辑?
使用向导创建到SQL Server的DSN连接时,可以将其链接到视图.在这种情况下,Access会将其识别为可编辑表.
When I create a DSN connection to SQL Server using the wizard, I am able to link it to a view. In this case, Access recognizes it as an editable table.
但是,如果我使用无DSN连接到使用vba代码的视图( https://support.microsoft.com/zh-cn/kb/892490 ),它作为不可更新的表链接.
But if I use a DSN-less connection to a view using vba code (Method 1 from https://support.microsoft.com/en-us/kb/892490), it is linked as a table that is NOT updatable.
我不知道为什么会有区别,但是如何连接到SQL Server中的视图(作为表或Access中的查询)并使其可更新?
I don't know why there is a difference, but how can I make a connection to a view in SQL Server (either as a table or a query in Access) and have it be updatable?
当我使用SQL Server中的表而不是视图建立无DSN的连接时,它在Access中是可更新的.我猜想我的问题与没有唯一ID的视图有关,但是我很困惑为什么DSN连接可以更新而没有DSN的视图不能更新.
When I make a DSN-less connection using a table in SQL Server rather than a view, it is updatable in Access. I would have guessed my problem has to do with views not having a unique ID, but I'm confused why a DSN connection can be updatable while DSN-less cannot.
不是因为它没有DSN,而是因为它是通过VBA创建的.如果通过Access GUI链接视图,它将要求您提供主键.
It's not because it's DSN-less, but because you created it via VBA. If you link the view via the Access GUI, it asks you for the primary key.
但是通过VBA,它不知道主键,因此链接的视图不可更新.对于表,Access会通过ODBC自动获取主键,因此该表可以工作.
But via VBA, it doesn't know the primary key, so the linked view is not updateable. With a table, Access gets the primary key automatically via ODBC, so the table works.
解决方案::通过VBA链接视图后,设置主键:
Solution: set the primary key after linking the view via VBA:
S = "CREATE INDEX PrimaryKey ON MyViewName (MyPrimaryKeyField) WITH PRIMARY"
DB.Execute S
如果您有很多视图,并定期重新链接它们(例如,从开发人员转到生产数据库),则对它们的名称和PK进行硬编码就变得不切实际.我编写了一个函数,用于从链接的视图中检索所有主键索引,并在链接后重新创建它们.
如果您愿意,我可以进行挖掘.
If you have many views, and re-link them regularly (e.g. going from dev to production database), it becomes impractical to hardcode their names and PKs. I wrote a function to retrieve all primary key indexes from linked views, and re-create them after linking.
If you want, I can dig it up.
修改:
这就是我要做的:
This is what I do:
' This function returns the full DSN-less connect string
Private Function ODBC_String() As String
' In the real world there are several constants and variable in there
ODBC_String = "ODBC;DRIVER={SQL Server};SERVER=aaa;DATABASE=bbb;UID=ccc;PWD=ccc;LANGUAGE=us_english;TRUSTED_CONNECTION=No"
End Function
要首次链接表或视图,我使用了此方法(strTable是表/视图的名称):
To link a table or view the first time, I use this (strTable is the table/view name):
DoCmd.TransferDatabase acLink, "ODBC", ODBC_String(), acTable, strTable, strTable, False, True
对于表,主键(PK)是自动确定的.对于视图,我将获得访问"对话框窗口以指定PK,就像我手动链接视图一样.
PK信息存储在TableDef对象中的链接视图中,因此我不必在任何地方对其进行硬编码.
For tables, the primary key (PK) is determined automatically. For a view, I get the Access dialog window to specify the PK, same as if I link the view manually.
The PK information is stored in the TableDef object for the linked view, so I never have to hardcode it anywhere.
要存储所有链接视图的PK信息,我有此表(为简单起见,它是Access前端中的本地表):
To store the PK information for all linked views, I have this table (it's a local table in the Access frontend for simplicity):
t_LinkedViewPK
ViewName Text(100)
IndexFields Text(255)
和此功能.所有视图(仅 视图)都称为"v_ *",因此我可以按名称列出它们.
我实际上不确定是否可以从TableDef对象确定它是否指向表或视图.
and this function. All Views (and only Views) are called "v_*", so I can list them by name.
I'm actually not sure if you can determine from a TableDef object whether it points to a table or view.
Private Sub StoreViewPKs()
Dim TD As TableDef
Dim idx As index
Dim FD As Field
Dim RS As Recordset
Dim S As String
' DB is a global Database object, set to CurrentDB
DB.Execute "Delete * From t_LinkedViewPK"
Set RS = DB.OpenRecordset("t_LinkedViewPK")
For Each TD In DB.TableDefs
If TD.Name Like "v_*" Then
' Views must have exactly one index. If not: panic!
If TD.Indexes.Count <> 1 Then
MsgBox "View " & TD.Name & " has " & TD.Indexes.Count & " Indizes.", vbCritical
Stop
End If
Set idx = TD.Indexes(0)
' Build field list (the index may contain multiple fields)
S = ""
For Each FD In idx.Fields
If S <> "" Then S = S & ", "
S = S & FD.Name
Next FD
RS.AddNew
RS!ViewName = TD.Name
RS!IndexFields = S
RS.Update
End If
Next TD
RS.Close
End Sub
当我更改表或视图结构或更改源数据库时(通过更改ODBC_String()
的输出来完成),我调用此函数:
When I make changes to table or view structures, or change the source database (this is done by changing the output of ODBC_String()
), I call this function:
Public Function Sql_RefreshTables()
Dim TD As TableDef
Dim S As String
Dim IdxFlds As String
DB.TableDefs.Refresh
' save current Indizes for Views (recreated after .RefreshLink)
Call StoreViewPKs
For Each TD In DB.TableDefs
If Len(TD.Connect) > 0 Then
If Left(TD.Connect, 5) = "ODBC;" Then
Debug.Print "Updating " & TD.Name
TD.Connect = ODBC_String()
TD.RefreshLink
' View?
If TD.Name Like "v_*" Then
IdxFlds = Nz(DLookup("IndexFields", "t_LinkedViewPK", "ViewName = '" & TD.Name & "'"))
If IdxFlds = "" Then Stop
' Create PK
S = "CREATE INDEX PrimaryKey ON " & TD.Name & " (" & IdxFlds & ") WITH PRIMARY"
DB.Execute S
End If
End If
End If
Next TD
DB.TableDefs.Refresh
End Function
注意:
代替表t_LinkedViewPK
,可以使用字典对象.但是在进行开发时,将其作为实际表非常有用.
Note:
Instead of the table t_LinkedViewPK
, a dictionary object could be used. But while developing this, it was very useful to have it as an actual table.