I have a windows application written in VB.net. After finishing it I'll setup the program in more than one pc. I want to connect the program in all PCs to one database in another PC using Microsoft Access, and I also want to limit the level of access of the users to the database in my program.
How can I do it? Many thanks.
Access is capable of handling multiple users, however once you get over 3 or 4 concurrent users you will start to notice that MS Access doesn't scale well. Access is designed for the professional but not an enterprise.
Microsoft SQL Server (Express edition is free - upto 4GB space) is designed for a large number of concurrent users.
I also want to limit the level of access of the users to the database in my program.
You can use folder Permissions if you wish to restrict access to the file. Personally in my old VB6 apps that used MS Access I called the file db.resources rather than db.mdb. This is because a.resources file cant be downloaded if it is hosted online (ref DotNetNuke) and also so people dont know which program to open the file in.
If you need role based security you need a enterprise level database such as SQL Server.
I want to connect the program in all PCs to one database in another PC using Microsoft Access.
Here is how you can have two computers share the same database.
a. Choose the main PC that will host the database
b. Host the database in a folder that is shared to the other users
c. Physically go over to the PC that isn't hosting the database, create a text fileon the desktop.
d. Rename the file extension from .txt to .udl and press enter
e. Double clcik the udl file and enter these settings and navigate to the shared folder that hosts the shared database:
f. Once the Test Connection is successful, close the Data Link Properties window.
g. Right click the UDL file on the desktop and choose Open With and open with notepad
h. You will see your connection string:
[oledb] ; Everything after this line is an OLE DB initstring
Provider=Microsoft.ACE.OLEDB.12.0;Data
Source=\\PCName\c$\temp\Database1.accdb;Persist Security Info=False
i. Set the second pc to use the networked connection string.
Access is perfectly capable to handle 2 users connecting to the same database. However this is not the main strenght of Ms-Access. So, if you plan to grow the user base it's better to start from the beginning with SqlServer Express (or MySql).
You don't need to use asp-net for this scenario if the user are on the same local network.
You are only required to prepare a valid connection string to identify the network location where you install the database. Of course, the PC hosting the database should share the network location and give read/write permissions to all users requiring the access to the database. (This could be the most complicated part depending on where you share the database)
Related
I am trying to find the best procedure to get data from our SQL server at headquarters to update apps running on local machines in various locations not connected to our network. Our current data and application is in Foxpro where you simply copied the data file, so I am not very familiar with using SQL databases.
The field app uses localdb and users don't save anything to the database. When the app opens it checks a web site to for updates. I tried detaching our HQ .mdf and .ldf, downloading it and overwriting it on the local machine, but localdb would not attach to the new file (same name). I thought localdb closes and detaches when the application closes , but maybe I am wrong. I also wonder if I need the log file since no changes are made and I dont need to rollback anything. I have searched for a good article on this topic but haven't found anything. This must be a fairly common scenario in many companies.
You want to look into using replication, probably snapshot replication. This allows you to distribute on whatever schedule is applicable to send one or more tables, or other objects, to off site sql server instances. You can use Http to send data.
I am using ADO to connect to an access database from an excel spreadsheet using code written in vb. The spreadsheet allows someone to retrieve files stored locally on my machine according to what they enter in certain cells and from interrogating the database. This has worked well which presents the frightening prospect of me now feeling encouraged!...
It is my wish to give a copy of my spreadsheet to people but retain the files and database on my own computer or a dedicated server. ( I do not want the users to be able to access anything other than a view onto the data or the files that I allow them to access). I totally appreciate their are a myriad of alternative technologies that I could and might need to achieve this. But I really am quite a simpleton and would like to be able to simply amend my connection string with something that uses an IP address and similarly with the files. Is this even possible? Can someone advise me where to even start looking for a solution if it is not? I've browsed through stuff on VPN's, application servers, ASP's etc. without even knowing if it is relevant and, as I say, I need the dumbsters solution. I'm happy to read - but what......should I look at VB.net?
A VPN would allow a similar setup to what you have now in as much as your would need to modify the connection string and file paths (to network share paths) but has drawbacks:
Users/you would need to configure a VPN client
Your machine would be the host so would need to be always-on with sufficient bandwidth
Users would be logging on to your machine so you would need to manage access rights/security
This is difficult to scale and a pain in to manage, which is something that is also true of attempting to serve Access content over the internet.
A more standard way to do this would be to:
Get an ASP.NET hosting account with SQL Server support (or set this up on your machine)
Migrate the Access data to SQL Server (which unlike Access is specifically designed to support multiple users over a network)
Update your VBA connection string and make any required changes to your SQL
Create an ASP page that reads the files stored on the server and returns their content
Modify the code you have that loads files from disk to instead query this ASP page over HTTP and read its contents
Retaining Access; you could also create a ASP page that executes queries, reads the data and converts it to XML returned to your spreadsheet for processing.
I've been struggling very hard to make this work. I'm using a software that uses paradox database, which I never used.
My problem is: I can open the program in multiple machines on the same time, but i can't seem to connect via ODBC when there is a program open in any machine (a .lck file maybe?). When noone is using the program I can connect without problems...
I understand that the lock file is there to protect the database integrity, but i wish just to make select commands via SQL directly into it... Is there any way to do it? A read-only connection maybe?
Thanks for the help!!
I had the same problem and I am living with this work around solution on the implementations of software I do where I work.
To make it work:
On the server machine of the paradox database, you have to create a new partition with the same letter where you will map on the client machines;
Share the unit drive;
On the client machines, map a new drive to the shared drive (repeating: the letter must be the same than in the server machine);
Put the database files in this drive;
Create the ODBC paradox system data source (it must be the 32 bit wizard) using the new directory for both Folder and Network folder;
Delete the existing .NET and .LCK before testing;
test...
I've read something about setting AUTO ODBC to TRUE on BDE too...
I'm new to ODBC and DSN's in general.
We have a product A that accesses a database "T" via a DSN D1 that has already been defined.
I'm now writing a test app testA that exercises various functionalities of product A and also needs to validate various database entries made by A.
For this, I am trying to access the same DSN D1 (that was setup for database T) to read from db and do the necessary validations.
I'm however having issues with that. I've setup the dsn, but when I do a SQLConnect with this dsn, I get a return value of -1.(I dont see any corresponding values for this return type either)n
Any clues on what this means and if I'm doing something wrong.Can we have 2 different processes or apps connect to the same DSN?
You can test access using a "udl" file. These files are largly misunderstood IMHO. They are simply a script that is used to launch the (db) connection library. You can create them by creating an empty file in notepad and changing the extension to .udl from .txt. You then double click on the file and configuer access to your database. (they launch a build in configeration applet). In my experience if a .udl file connects then any application will connect or 100% there is a problem with the application. If the udl file will not connect, then 100% there is a firewall or something probibiting access to the account being used to try to connect.
I know I used to need these things when (once upon a time) I was an Access developer (Access 97), but do I need a workgroup file to share a backend database with two other users?
I did the split database thing and gave each their own copy of the front-end, and I thought that simply putting the backend part on a shared file location would do it.
The others can read the database and run forms and such, but they can't add rows - I still can.
What am I missing?