We have an Access db that acts as a company-wide backend--containing a master list of contacts, clients, etc. Almost every other database relies on this one via linked tables. However, we would like to migrate this backend to SQL Server with as few interruptions/breakages as possible. Our thought was to replace the tables in the Access backend with linked ODBC tables (keeping the same name), however when trying this we found that other Access files could no longer see the tables. Is there a way to do this or will we have to change all linked tables throughout our company to point to the new SQL backend?
will we have to change all linked tables throughout our company to
point to the new SQL backend?
Yes. You can create a link to a TableDef which is a native table in another Access database --- that is what you have now. But Access will not allow you to create a link to a TableDef in another Access database when that TableDef is actually a link to an object in yet another database. In other words, you can't link to a link.
So you must change all the links which point to the migrated Access tables so that they will now point directly to the SQL Server tables.
Related
I am new into MS access. Earlier, I have linked the tables in MS access 2010 through SQL server. Now, today I replaced the existing database and restored updated backup file of same database.
My Questions is, do I need to re-link the database again to make sure tables which are linked in Access also gets updated?
Note: I have refreshed the linked tables in access.
If the table structure in the backup is 100% identical to the originally linked tables, you don't need to do anything.
The data is retrieved "live" from the server.
If there are differences, you need to re-link the tables, or run TableDef.RefreshLink for each linked table.
The table structure is only retrieved when linking the table, Access doesn't automatically retrieve changes in the structure (e.g. added columns).
I have a question. In SQL server, we can access a table or view in a different database by using the dot notation in the table name, so I believe that in SQL server, if we say just 'tablename' it will refer to the table name in the current active DB, but if we say 'DBname'.'Tablename' you can access the table in a different DB on the same server, and if you say 'serverName'.'DBName'.'tableName' we can access a table in a remote DB whose DBName is defined in a connection setting. I believe we can define a connection setting between two SQL server to access a different database. So, instead of copying the data from one DB to other and duplicate the same, it might be better to simply define a view.
Can anyone please help me if we can do so and how?
Using Linked Server you can access two different servers.
use the below link to add the linked server.
http://sqlserverplanet.com/dba/how-to-add-a-linked-server
When I create a new MVC application with EF, it creates all the views, models, controllers and logic for users to be able to log in, change passwords etc. The data is held in a MDF file in the app_data directory.
I used this for my users, and then had my own SQL Server 2008 database which was created code first using EF for all my other tables. When I wanted to reference a user from a table within this database, I used the ApplicationUser.Id.
Doing it this way, I have not got a foreign key between the table that holds the users and any other table in my custom DB, but thats a different topic.
The question I have, is how I can I stop this happening every time I create a new application, and how do I fix the issue I have now.
I have two different databases, when I just need one. have one database in SQL Server (which is what I want) and one in a file which I cannot convert to SQL Server as it was created in 2012, and I am using 2008 SQL Server.
I am wanting to now deploy this on a server where all data is read from SQL Server.
The way I see it, I need to somehow get all the tables it creates for Membership, and put them into the database I created, then change the connection string. However first off I don't know how I would do this, and second... WHY do I have to do this? How can I just have one database next time. Am I missing something?
After some research and messing around, I have answered my own question and think it may be useful for others.
I am using MVC 5 with the default ASP.NET Identity for my users.
What I found is that if I changed the connection string to point to my SQL server, it will create the database for me (the one that was previously a file in my app directory).
I then added a connection string to the same database for the context I created and it created all the tables for that in the same database.
The result is that I have one database with all my tables in.
I am attempting to keep a table in Sql server updated from an access table. Any time a change is made in the access table I would like that change reflected in the sql server table. The two tables can be identical. I have created an ODBC connection from access to sql server and can export the table to sql server; I just don’t know what must be done to keep that table updated. Any suggestions are appreciated.
Should this be implemented from within Access or within sql server?
Can you just add the SQL Server table to the Access database as a linked table? (Useful article on how to add linked tables)? That way users (let's hope there's not many!) of the Access database are in effect editing the SQL Server table directly.
If this isn't desirable then how about creating another table in the SQL Server database, and adding this to the Access database as a linked table. Then, add a trigger so that when an insert/update/delete is made to this table the same operation is done on your main table.
I think setting up a Linked Server in SQL Server could be easier to implement than an automatic export of data from Access.
According to the MSDN page,
Many types OLE DB data sources can be configured as linked servers, including Microsoft Access and Excel.
Server-on-SQL-2005-Server/
Access has no "event" that occurs when a row is updated/inserted/deleted that I know of. as JeffO points out data macros that could do what you want.
You could also periodically synch them. There are several techniques to periodically do the synch task (SQL Server Agent, Windows Service, Windows Scheduler, a timer in an application etc.), but still have to deal with all the problems that exist with synchronization if both tables can be modified, the worst being data conflict resolution. There is no easy solution for that.
Perhaps if you explained the problem you have that you are solving with synching data in SQL server and Access someone might be able to point you in the direction of a solution that doesn't have these problems.
I need to upsize a split Access database, i.e., one that's currently split between tow mdb files, a front-end and back-end. I see many webpages that in essence say, "run the Upsizing Wizard." My first, very basic question:
Should I be running this wizard in my front-end mdb or my back-end mdb?
I assume I don't want to link main mdb -> backend mdb -> sql server. Should I run the wizard on the backend mdb, and then in the frontend mdb change the linked tables to point to sql server rather than to the backend mdb? If so, how is this done? When I right-click and go into the Linked Table Manager for a table in the frontend (linked to the backend md), it only seems to let me choose a new mdb file.
I would agree with your first guess: you will want to run the wizard on the back-end mdb.
Once that's in SQL Server, also as you guessed, you'll want to link the front end to work with the SQL Server data. One way to do this is to set up an ODBC data source for your new SQL Server database and select that in the Linked Table Manager.
Open the Data Sources (ODBC) shortcut: in XP Pro, this is in the Control Panel under Administrative Tools. (If you don't see it, you probably don't have permission to create a data source, so you'll have to work with your network people to do this.) This will open the ODBC Administrator.
On the File DSN tab, click Add.... You'll see a list of available drivers. Select SQL Server and click Next. (If the front end is only being used on your machine, you can create a System DSN instead.)
Find a common location and name your data source.
Click Next and Finish. This will set up the first part of the data source, and will open the SQL Server data source wizard.
Name the data source and select the server on which you've put the upsized back-end database.
Change the rest of the settings as needed (you may not need to change much, but the scope of those changes may require a second question) and click through to Finish.
Once you have the data source set up, then Get External Data should give you the option to select it as your source. (In 2007, you can get there from the External Data ribbon. ODBC data sources are available under More.)
To expand a little further based on Matt's follow-up questions:
How you do it is a design choice. I recommend upsizing the back-end mdb because that would allow you to keep whatever forms and such you had in Access; I think it's less of a transition if your data is in SQL Server.
Before you upsized, your tables were linked to the back-end database, and the Linked Table Manager showed the links. After you set up the ODBC data source and linked those tables, it'll show that link. You'll view the links in two different ways because they're actually different types of links (Access vs. ODBC), even though the links may look the same in your front-end mdb.
Personally I have found that the upsizing wizard does a very bad job of determining correct datatypes. I would create the tables myself in SQL server using the datatypes I need, then move the data to the existing tables from Access. other wise you will be stuck with text data when you could use varchar or float when you really need decimal.
Once the data has been moved then I would delete the Access tables and link to the SQL Server tables.
Do not do anything without having a backup copy of the database first.
As a matter of standard paranoia, I would just make a backup copy of the existing files and run the Upsizing Wizard on the front end. If anything undesirable happens, just revert the changes by overwriting with the backup copy.
Update the front end, and it will import the back end tables before it upsizes. I did this a week ago with a successful result.
However, any queries that use -1 instead of Yes will fail. Any full table deletes on tables without a primary key will fail, and you will get different behaviour from that than you will by merely using a pass-through SQL query to truncate table. The trunc will delete all rows, the Access version may leave a blank.
Also you'll need to include dbSeeChanges anywhere you have a recordset opening on a table with an autonumber column data type. SQL changes these to Identity data types, then gripes before you try to open the table. Good luck.
Do it all in the front end
You can simply export the tables to SQL Server.
You can then delete the linked tables you have in your frontend.
Then link the connection to SQL Server
Check:
when you open tables you get records
all your queries run
compile your code
You will also have to consider how you are releasing the front end. If you are using a dsn file you will need to provide that to each user.
You will need to determine how the end user accesses SQL Server. Are you using a single login with the username and password stored in the connection?
You could also split your backend DB into multiple Access DB and link them in the frontend.