Readonly connection string to an access database

11
votes

I'm trying to connect to an Access database file using a System.Data.OleDb.OleDbConnection. I need to connect in readonly mode because another application uses it at the same time. I can connect to the database in read/write no problem but can't seem to find anywhere the correct string for readonly.

I've tried:

Provider=Microsoft.ACE.OLEDB.12.0;Data Source={0};Persist Security Info=False;Mode=Read

Provider=Microsoft.ACE.OLEDB.12.0;Data Source={0};Persist Security Info=False;Extended Properties="ReadOnly=true;"

Thanks.

EDIT:

(I should have put more information in the original question.)

I could connect successfully to the access database when it was on the local machine, but when I tried connecting to the access database on a remote machine with the connection string

Provider=Microsoft.ACE.OLEDB.12.0;Data Source={0};Persist Security Info=False;Mode=Read

I would get the following error:

System.Data.OleDb.OleDbException (0x80004005): The Microsoft Office Access database engine cannot open or write to the file '{0}'. It is already opened exclusively by another user, or you need permission to view and write its data.

My application is running in a windows service under the local system account.

2
ms-accessconnection-stringoledb
Try setting Mode to "adModeRead" (without quotes). See MSDN Reference. (Not making this an answer as I cannot validate if it will work or not, just going off MSDN data.) – Brad Butner
I tried setting Mode to 'adModeRead' but it throws a 'System.Data.OleDb.OleDbException (0x80040E73): Format of the initialization string does not conform to the OLE DB specification.' Thanks for the suggestion. – Smiffy

2 Answers

3
votes

I think that has to be handled either by user permissions that the DB admin would control, or with different cursor types for your recordsets, which you would control. I don't think the connection string specifies access mode, it just gets you there. ;)

2
votes

The real problem is that Excel leaves the connection open until the file is closed.

In Excel 2007+, the MaintainConnection setting is set to true by default. You need to go into the vb editor and use code to turn it to false. I haven't seen a way to do this through the visual interface. Even if you set the connection string to readonly, it will lock an access database (from my experience).

For a pivottable connection:

Sheets("sheet1").PivotTables("pivottable1").PivotCache.MaintainConnection = False

For QueryTable:

Range("A2").Select
Selection.ListObject.QueryTable.MaintainConnection = False
Selection.ListObject.QueryTable.Refresh BackgroundQuery:=False

By setting it to false, the table will connect, run the command, then disconnect, releasing the lock.