I am unsing entity framework in my web application. Earlier everything was working fine. But then I deleted database from Sql Server. After that whenever I run the application, I get the following exception :
The underlying provider failed on open entity framework
Isn't it true that if we delete the database from Sql Server and again run the application, database is again created?
Can you show some details about connection string. I basically want to check the authentication you are using.
Demo for setting a typical authentication : http://msdn.microsoft.com/en-us/library/ff649314.aspx
Another possibility can be with connection pooling. Try explicitly closing the connection(if there are any open connections)
db.Database.Connection.Close();
Entity framework will recreate your database on application start assuming the following:
You have permission to create databases in SQL
A connection string is specified correctly (if it was working before this should be fine)
You are using CodeFirst or ModelFirst strategies for databases (ie if you generated an EDMX off an existing database it wont recreate it for you)
I had a similar error and it was due to the connection problem.
Usually you need to open your *.EDPS file under your entity (EDML) and check your connection string and make sure it has got a correct setting especially your Default Oracle home.
Related
I have a ASP.NET application that uses application services to manage user roles. This application worked fine when I was using a local database. When I transitioned to Azure, the main data tables still work but I am unable have user's login or create new accounts because the Application table cannot be found. Previously, the application services created these tables automatically when using a local database. The connection string name appears accurate. This is my first attempt at Azure...is there something I'm missing?
The error is "The entity type Application is not part of the model for the current context"
For additional context: When I try to create the membership tables in the Azure database using aspnet_regsql.exe, I get the following error: "An error occurred during the execution of the SQL file 'InstallCommon.sql'. The SQL error number is 40508 and the SqlException message is: USE statement is not supported to switch between databases. Use a new connection to connect to a different database."
I am getting the ORA-24778: cannot open connections, what are the possible causes?
We have a number of applications deployed in WAS7 profile and they connect to a number of schemas in Oracle 11g.
One of the schema is connecting through other schema via public DB link.
I cannot identify a solution for this cause.
After restarting the WAS7 profile, it is ok for a while and again start hitting the error.
Pls help!!
I assume you missed to tell us a few details:
You are using XA
You are using XA in combination with database links
You are using shared database links
The ora-24778 is not happening all the time
Either you haven't configured shared server option or you are not connected to a shared server. However Oracle requires you to user shared server if you want to use XA and database links.
Or the parameter OPEN_LINKS_PER_INSTANCE is not set sufficiently. Keep in mind mind that there is also a open_links init.ora parameter. The open_links parameter does not apply to XA.
This error can occur when you invoke a dblink in a existing transaction.
Apparently, using AttachDbFilename and user instance in your connection string is a bad way to connect to a DB. I'm using SQL server express on my local machine and it all seems to work fine. But what's the proper way to connect to SQL server then?
Thanks for your explanation.
Using User Instance means that SQL Server is creating a special copy of that database file for use by your program. If you have two different programs using that same connection string, they get two entirely different copies of the database. This leads to a lot of confusion, as people will test updating data with their program, then connect to a different copy of their database in Management Studio, and complain that their update isn't working. This sends them through a flawed series of wild goose chase steps trying to troubleshoot the wrong problem.
This article goes into more depth about how to use this feature, but heed the very first note: the User Instance feature has been deprecated. In SQL Server 2012, the preferred alternatives are (in this order, IMHO):
Create or attach your database to a real instance of SQL Server. Your connection string will then just need to specify the instance name, the database name, and credentials. There will be no mixup as Management Studio, Visual Studio and your program(s) will all be connecting to a single copy of the database.
Use a container for local development. Here's a great starter video by Anna Hoffman and Anthony Nocentino, and I have some other resources here, here, and here. If you're on an M1 Mac, you won't be able to use a full-blown SQL Server instance, but you can use Azure SQL Edge if you can get by with most SQL Server functionality (the omissions are enumerated here).
Use SqlLocalDb for local development. I believe I pointed you to this article yesterday: "Getting Started with SQL Server 2012 Express LocalDB."
Use SQL Server Compact. I like this option the least because the functionality and syntax is not the same - so it's not necessarily going to provide you with all the functionality you're ultimately going to want to deploy. Compact Edition is also deprecated, so there's that.
Of course if you are using a version < SQL Server 2012, SqlLocalDb is not an option - so you should be creating a real database and using that consistently. I only mention the Compact option for completeness - I think that can be almost as bad an idea as using AttachDbFileName.
EDIT: I've blogged about this here:
Bad Habits : Using AttachDBFileName
In case someone had the problem.
When attaching the database with a connection string containing AttachDBFile
with SQLEXPRESS, I noticed this connection was exclusive to the ASP.NET application that was using the database. The connection did block the access to all other processes on the file level when made with System.Data.SqlClient as provider.
In order to assure the connection to be shareable with other processes
instead use DataBase to specify the database name in your connection string
Example or connection string :
Data Source=.\SQLEXPRESS;DataBase=PlaCliGen;User ID=XXX;password=ZZZ; Connect Timeout=30
,where PlaCliGen is the name (or logical name) by which SQLEXPRESS server knows the database.
By connecting to the data base with AttachDBFile giving the path to the .mdf file
(namely : replacing DataBase = PlacliGen by AttachDBFile = c:\vs\placligen\app_data\placligen.mdf) the File was connected exclusively and no other process could connect to the database.
I have a ASP.NET web application which does some changes on a table in SQL Server 2008 R2.
On this table there is a trigger that does updates on another table in another database on the same database server.
When saving the changes I'm having the following error:
- The error message: The underlying provider failed on Commit.
- InnerException: This SqlTransaction has completed; it is no longer usable.
Also allowing the database user to connect to the other database isn't working.
Somebody knows how I can make this work?
The trigger is not related to Entity Framework.
The trigger fires when changes are made to the table irrespective of where that change came from.
This is probably a rights issue, the system is attempting to make the change to the second database with the security context that was used to connect to the first database. It the change that was caused by the trigger fails, then everything in the same transaction will fail.
Since you are accessing 2 databases in a transaction, you are using MSDTC, make sure that it is started and that you have rights to it.
I have a Sql Server 2008 Express database file that's currently being used by an ASP.NET application, and I'm not sure how to query the database without taking the website down.
I'm unable to copy the database files (.mdf and .ldf files) to another directory, since they're in use by the web server. Also, if I attach the databases to an instance of the sql server (using the 'Create Database [DB name] on (filename = '[DB filename.mdf]') for attach;' command at the sqlcmd prompt), then the application pool user becomes unable to access the database (i.e. the webpages start producing http 500 errors. I think this might have to do with the username for the application pool becoming somehow divorced from the login credentials in the sql server database).
Any suggestions? I realize this is probably a newbie question, since it seems like a rather fundamental task. However, due to my inexperience, I really don't know what the answer is, and I'm pretty stumped at this point, since I've tried a couple of different things.
Thanks!
Andrew
if I attach the databases to an instance of the sql server (using the 'Create Database [DB name] on (filename = '[DB filename.mdf]') for attach;' command at the sqlcmd prompt),
Don't do this to a live database - it's attempting to be setup an MDF to be written to by two different databases...
Use Backup/Restore
As you've found, Attach/ReAttach requires the database to be offline - use the Backup/Restore functionality:
MSDN: Using SSMS to Backup the Database
MSDN: Using SSMs to Restore the Backup
Be aware that the backup/restore doesn't maintain logins (& jobs if you have any associated with the database) - you'll have to recreate & sync if using an account other than those with uber access.
Maybe Linked Server would work?
Another alternative would be to setup another SQL Server Express/etc instance on a different box, and use the Linked Server functionality to create a connection to the live/prod data. Use a different account than the one used for the ASP application...