I'm building a school project application that has a connection to a SQL Server database.
On my computer, the program works flawlessly, however, when I built it and send it to another computer for testing, I'm getting an unhandled exception that I can only assume is the connection not being successful.
I'm using an app.config, with the connection string as follows:
<connectionStrings>
<add name="TEAMSConnectionString"
connectionString="Data Source=.\MYSQL;Initial Catalog=TEAMS;Integrated Security=True"
providerName="System.Data.SqlClient" />
</connectionStrings>
Can someone help me write a connection string that should work on all computers?
connectionString="Data Source=.\MYSQL
It looks like your database is located on your local machine. That's what the . means in the connection string. It's short for localhost. So it doesn't work on the other computer because it is looking for the database on its own localhost, or on itself.
To get this to work on other machines, you will either need to migrate your database to a server that is more widely available (good idea) or somehow give the other computers network access to your computer (not a good idea).
But either way, the connection string will need to point to something else other than "localhost" or every computer that runs the app will try and find the database on itself.
Hope this helps!
Related
Cannot create SQL connection with this connection string:
<connectionStrings>
<add name="SchoolContext"
connectionString="Server=.;Database=SchoolContext;Integrated Security=True;"
providerName="System.Data.SqlClient" />
</connectionStrings>
I get this error:
A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server)
but there's no problem with this connection string:
<connectionStrings>
<add name="SchoolContext"
connectionString="Server=DESKTOP-7M2F9E2\MOJTABA;Database=SchoolContext;Integrated Security=True;"
providerName="System.Data.SqlClient" />
</connectionStrings>
Why can it not connect to local?
That's most probably cause you are trying to connect to a named instance called MOJTABA and not to a default instance as can be seen from your posted code connectionString="Server=DESKTOP-7M2F9E2\MOJTABA. You can as well say Server=localhost\MOJTABA or .\MOJTABA
I would try this:
<connectionStrings>
<add name="SchoolContext" providerName="System.Data.SqlClient" connectionString="Server=.\MOJTABA;Database=SchoolContext;Integrated Security=True;"/>
</connectionStrings>
Server=.\MOJTABA means: local machine (.), MOJTABA database server instance.
The dot alone is not enough to know which instance to connect to.
This is not a C# problem, so the tag for that was wrong. The Network code does not care if the other end is on the same computer, same switch or the Voyager 2 Probe.
Proper installation and administration of a SQL Server is a totally seperate mater from programming.
And finally connection strings are a mater so complicated, there is a dedicated webpage for that.
This is either a SQL Server Administration issue (the instance you try to connect does not exists/is not allowed to take connections) or a Connection String issue (you formated it faulty). It is really impossible to tell without knowing how exactly your Environment looks, wich is something only you can realy do.
I am writing a Windows Forms application, where I want to save data inside the application. For the reason I used a serviced-based database with a .mdf database file, and I use Entity Framework.
So far everything is working fine until I released the file and opened it on another computer. The application opened and everything worked fine but when it comes to the database interaction, it throws a big error like this:
************ Exception Text ************
System.Data.Entity.Core.EntityException: The underlying provider failed on Open.
System.Data.SqlClient.SqlException: A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 50 - Local Database Runtime error occurred. The specified LocalDB instance does not exist.)
Here a screenshot of the error: https://www.dropbox.com/s/gwban6ab97c6fya/22093543_10213995193571435_760919436_n.png?dl=0
In case you need the project its uploaded to here: https://www.dropbox.com/s/ubpc683ggtihh6k/usercontrol.zip?dl=0
I have tried in so many ways but nothing is working, same thing happens for the installer version as well.
Can anyone help me on this please?
Here are my connection strings:
<add name="DatabaseEntities"
connectionString="metadata=res://*/dbModel.csdl|res://*/dbModel.ssdl|res://*/dbModel.msl;provider=System.Data.SqlClient;provider connection string="data source=(LocalDB)\MSSQLLocalDB;attachdbfilename=|DataDirectory|\Database.mdf;integrated security=True;MultipleActiveResultSets=True;App=EntityFramework""
providerName="System.Data.EntityClient" />
<add name="OPLCheque.Properties.Settings.DatabaseConnectionString"
connectionString="Data Source=(LocalDB)\MSSQLLocalDB;AttachDbFilename=|DataDirectory|\Database.mdf;Integrated Security=True"
providerName="System.Data.SqlClient" />
I'm pretty sure this post would be flagged as duplicate since a similar question has been answered multiple times already, but here you go.
You are using LocalDB which means it cannot be shared since it runs on SQL Server Express.
If you simply want a LocalDB, see this answer to implement it after publishing your WinForms app.
Basically you want to publish your app with prerequisite components so you should publish those along your application.
If you want to use a single database to be shared between instances of your application, learn how to setup one using SQL Server here.
Afterwards, learn what connection string format you should use.
Sample to connect via IP Address:
connetionString="Data Source=IP_ADDRESS,PORT;
Network Library=DBMSSOCN;Initial Catalog=DatabaseName;
User ID=UserName;Password=Password"
See this for more.
If ever you plan on using a shared database, better make sure that the connection string that your database context should use is specified.
Config:
<add name="DefaultConnection" connectionString="" providerName="" />
Database Context:
public DbContext()
: base ("DefaultConnection")
{
}
I tried to find information about this on the web and Stack Overflow, but none of the responses could help me solving my problem.
I'm working with C# and SQL Server. I'm using code from an existing project, which project connects to an SQL Server instance to manage data. This project uses EntityFramework.
Now I want to use a local instance of SQL Server, precisely SQL Server Express, for development purpose. But I can't figure out how to connect to this local instance.
Connecting to the remote SQL Server works perfectly, using this connection string:
<add name="ProjectEntities" connectionString="metadata=res://*/Project.Project.csdl|res://*/Project.Project.ssdl|res://*/Project.Project.msl;provider=System.Data.SqlClient;provider connection string="data source=111.111.111.666\(local), 1433;initial catalog=PROJECT;persist security info=True;user id=user;password=password;MultipleActiveResultSets=True;App=EntityFramework"" providerName="System.Data.EntityClient" />
But if I modify it to use my local instance:
<add name="ProjectEntities" connectionString="metadata=res://*/Project.Project.csdl|res://*/Project.Project.ssdl|res://*/Project.Project.msl;provider=System.Data.SqlClient;provider connection string="data source=.\PROJECT, 1433;initial catalog=PROJECT;persist security info=True;user id=user;password=password;MultipleActiveResultSets=True;App=EntityFramework"" providerName="System.Data.EntityClient" />
it doesn't work.
I tried with putting the source in "MAC\PROJECT" also, it does not change anything. Using the udl file workaround to test connection parameters is totally OK both with "MAC\PROJECT" and ".\PROJECT" and the right credentials.
I can't figure out why my project connect to the database perfectly using the remote server but not the local one. Am I missing something?
Right after posting this question I found the answer.... The old connection string gives a port number, which is not needed when connecting to the local instance.
I have a WinForms application that connects to a SQL Server database. I use the following connection string
data source=MyPC\SQLEXPRESS;initial catalog=MyDB; trusted_connection=true;
Problem is, I need to create an installer for the application, but I do not know the name of the target computer. How can I define my connection string, so it will work on any computer the application is installed on?
Thank you for your help.
I still don't have the privilege to comment, so I'm posting as an answer.
using "Localhost" in the data source would do the trick
so your connection string will be like this:
connectionString="data source=localhost\SQLEXPRESS;initial catalog=MyDB; trusted_connection=true;"
I'm cloning a local C#-SQL Windows Forms application to a new laptop. I've successfully cloned the C# project and back-up-and-restored the SQL database to the new machine, but the new project is unable to read/query any data from the new, cloned SQL database.
Since the SQL DB is local, the LINQ-to-SQL addressing is slightly different on account of the computer having a different name. So, I deleted the SQL table representations from the existing LINQ .dbml's graphical interface, removed the old server connection from the Server Explorer, added the new server connection, and click-and-dragged the table objects from the Server Explorer's new Data Connection object to the now-empty .dbml file.
Upon rebuilding and running the application in debug mode, I found that the dropdown menus which pull from the SQL DB are empty. Upon trying a button function which pulls from the database, I get the following error:
SqlException was unhandled
A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified)
(The cloned SQL server is configured to allow remote connections, TCP/IP is enabled in SQL, and the original C#-SQL application works without a hitch.)
Check in your Web.Config and make sure that your Connection String is set up correctly. Also check to make sure that when you initialize your DataContext that you are using the correct Connection string from your Web.Config.
Sometimes when you remove dbs from the dbml, it doesn't completely clear the web.config of the old entries. Look for a line like this in your designer.cs file:
public SomeDbDataContext() :
base(global::System.Configuration.ConfigurationManager.ConnectionStrings["SomeDbConnectionString"].ConnectionString, mappingSource)
{
OnCreated();
}
Compare it with the connectionStrings in your web.config
<connectionStrings>
<add name="ApplicationServices" connectionString="data source=.\SQLEXPRESS;Integrated Security=SSPI;AttachDBFilename=|DataDirectory|aspnetdb.mdf;User Instance=true" providerName="System.Data.SqlClient" />
<add name="someDBConnectionString" connectionString="Data Source=SomeServer;Initial Catalog=SomeDB;Integrated Security=True" providerName="System.Data.SqlClient" />
<add name="theOLDDBConnectionString" connectionString="Data Source=SomeServer;Initial Catalog=OldDB;Integrated Security=True" providerName="System.Data.SqlClient" />
</connectionStrings>
I would check a few things:
1) Is SQL Server started on the new machine?
2) Is the firewall configured to allow SQL connections?
3) Is the client connection mechanism (named pipes, tcp/ip) also configured in SQL Server.
4) Is there a valid network connection in the new machine (we used to have a lot of problems on laptops when they were not connected to the network).
You might have much better luck if you change the SQL Server machine name to . or (local) if you are always going to have the DB installed on the same machine as the app.