Still celebrating National IT Professionals Day with 3 months of free Premium Membership. Use Code ITDAY17

x
?
Solved

Persistent connection to MS Access using VB.Net

Posted on 2015-02-17
7
Medium Priority
?
242 Views
Last Modified: 2016-02-11
I've read that a persistent connection from each client application to an Access file can improve performance in a multi-user environment. The connection is opened when the app is started and closed when the app is closed. Can such a connection be established from a vb.net application? If so, how?
0
Comment
Question by:Tim313
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
  • 2
  • 2
  • +1
7 Comments
 
LVL 75
ID: 40615877
Yes ... it makes a HUGE difference.

Do you have access to DAO via vb.net ?

In VBA, all you actually have to do is execute an OpenDatabase command. That will create the LDB (lACCDB) file.

mx
0
 
LVL 58
ID: 40616159
I would add that it depends on the app.   If you are already more or less holding a connection open with the way the app works (say with a menu utility) , then no, you won't see any difference.

 What happens and where the recommendation comes from is that once a client has no more active connections, the database is closed for that user.   When they go to do something again, the database is opened again.

 The overhead of getting a user logged into JET and the database opened is fairly expensive overall.

 So by holding a persistent connection (be it opening the DB itself or even a table), you avoid the repeated closing/opening.

 In vb.net, you'd create a class to open a table, returning a record set (ADO or DAO, doesn't matter) from a table with no records (SELECT * FROM <table> WHERE 1=0), and then hold an instance of that class open until the app closes.

Jim.
0
 
LVL 85
ID: 40616187
Generally with .NET you should open the connection when needed, do the work, then close the connection immediately. ADO.NET uses connection pooling, and you should allow ADO.NET to manage your connections. .NET handles connections differently than does Access, so it'd be hard to say if this method would work with .NET. That said, as JimD mentions, I'm not sure how ADO.NET works in regard to file-based databases, like JET/ACE. You may find that opening a connection will improve performance.

Note that if you have a Main form that's always open you could do the same in the Load event of that form. Just do something like this:

Dim con As New OleDb.Connection
con.ConnectionString = "YourConnectionString"
con.Open
Dim cmd As New OleDb.Command
cmd.Connection = Con
cmd.CommandText = "SELECT IDField FROM YourTable WHERE 1=0"
Dim dt As New Datatable
dt.Load(cmd.ExecuteReader)

Don't use the "Using" construct, since doing so would destroy those objects after the code block ...
0
Concerto's Cloud Advisory Services

Want to avoid the missteps to gaining all the benefits of the cloud? Learn more about the different assessment options from our Cloud Advisory team.

 

Author Comment

by:Tim313
ID: 40616243
Thanks guys, all good information.

Once the persistent connection is opened, is this the connection I need to use for all subsequent queries in my app (currently each query opening/closing a connection)?
0
 
LVL 85

Accepted Solution

by:
Scott McDaniel (Microsoft Access MVP - EE MVE ) earned 1000 total points
ID: 40616265
is this the connection I need to use for all subsequent queries
IMO, no. You should create/open a connection when needed, and close it when you're finished.
0
 
LVL 58

Assisted Solution

by:Jim Dettman (Microsoft MVP/ EE MVE)
Jim Dettman (Microsoft MVP/ EE MVE) earned 1000 total points
ID: 40616333
<<is this the connection I need to use for all subsequent queries in my app (currently each query opening/closing a connection)? >>

 No, there is nothing special about this connection.  All it's doing is making sure the database doesn't close when you stop doing everything else.

Jim.
0
 

Author Closing Comment

by:Tim313
ID: 40616481
Thanks Scott and Jim!
0

Featured Post

Veeam Disaster Recovery in Microsoft Azure

Veeam PN for Microsoft Azure is a FREE solution designed to simplify and automate the setup of a DR site in Microsoft Azure using lightweight software-defined networking. It reduces the complexity of VPN deployments and is designed for businesses of ALL sizes.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

In Part II of this series, I will discuss how to identify all open instances of Excel and enumerate the workbooks, spreadsheets, and named ranges within each of those instances.
Microsoft Access is a place to store data within tables and represent this stored data using multiple database objects such as in form of macros, forms, reports, etc. After a MS Access database is created there is need to improve the performance and…
Basics of query design. Shows you how to construct a simple query by adding tables, perform joins, defining output columns, perform sorting, and apply criteria.
In Microsoft Access, when working with VBA, learn some techniques for writing readable and easily maintained code.
Suggested Courses

715 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question