I have a C# program to connect to SQL Server. It works fine at the test computer with SQL Server 2012 but does not work on the production environment with 2008. At the production environment, it reports exception as such,
Unhandled Exception: System.Data.SqlClient.SqlException: A network-related or in
stance-specific error occurred while establishing a connection to SQL Server. Th
e server was not found or was not accessible. Verify that the instance name is c
orrect and that SQL Server is configured to allow remote connections. (provider:
Named Pipes Provider, error: 40 - Could not open a connection to SQL Server) --
-> System.ComponentModel.Win32Exception: Access is denied
here is my connection code,
connStrSql = "Server=" + sqlserver + "; Database=" + sqldb + "; Trusted_Connection=True";
SqlConnection sqlConn = new SqlConnection(connStrSql)
sqlConn.Open();
The target platform is x86 and target framework is 4.5. The funny thing is that Excel and ODBC config can connect to the database without complain. Does C# program use different way connecting to SQL Server? How can I fix the problem?
There are many possible reasons why you can not connect to an SQL Server database. This is a great trouble shooting guide to help you solve the above error.
Briefly:
Is the SQL Server services running?
Has the SQL Server TCP/IP settings been configured?
Does the firewall settings allow SQL Server through?
Has SQL Server itself been configured allow remote connections?
Other things to consider
Is the value of sqlserver correct?
Has the client protocol you are using to connection to SQL Server, such as Named Pipes, been enabled?
One of the most common reasons for a remote connection being refused in newer versions of SQL Server is the SQL Browser is not turned on. It is off by default after an install. Another common reason is you don't have the particular protocol (in this case net pipes) turned on, but I would check the SQL Browser first, as it is probably turned off.
Might be firewall/security restriction in production - Try running against a local SQL2008 db because I just ran the code against SQL2008 and it does work with a correct sqlserver and sqldb parameter and change the line below ( missing ; )
SqlConnection sqlConn = new SqlConnection(connStrSql);
Try this for SQL Server connection:
Attach a database file on connect to a local SQL Server Express instance
Server=.\SQLExpress;AttachDbFilename=C:\MyFolder\MyDataFile.mdf;Database=dbname;
Trusted_Connection=Yes;
Attach a database file, located in the data directory, on connect to a local SQL Server Express instance
Server=.\SQLExpress;AttachDbFilename=|DataDirectory|mydbfile.mdf;Database=dbname;
Trusted_Connection=Yes;
Try this Excel Connection string
Provider=Microsoft.ACE.OLEDB.12.0;Data Source=c:\myFolder\myExcel2007file.xlsx;
Extended Properties="Excel 12.0 Xml;HDR=YES;IMEX=1";
If any other problem regarding connection string, refer this site
MS-Excel: http://www.connectionstrings.com/excel/
MS SQL Server: http://www.connectionstrings.com/sql-server/
Thanks,
NB
Related
I have a database called Library created in SQL Server 2014 under my locally created server instance. I am using that database as the datasource in my windows form application. It is working perfectly when on my computer, but when I run it on other machines, it stops with the error
Unhandled exception occurred...
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 connection to SQL Server)
I have started all services from configuration manager and have enabled tcp/ip under protocols for MSSQLSERVER. Is there any way I can accomplish this, or do I have to shift to local db?
Make sure that your connection string includes your remote machine name as part of the "Data Source", so something like :
connectionString="Data Source=machinename\SQLExpress;Initial Catalog=mydbname;Integrated Security=True"
note that this connection string will target a db name "mydbname", under the machine machinename which has a SQL Express instance.
if that didn't work let me see your connection string.
When I try to connect to the MS SQL server in the local domain with SQL with SQL server authentication using the following code fails:
SqlConnection sql = new SqlConnection(conString);
sql.Open();
sql.Close();
I can connect to my local SQLExpress test database just fine, using either windows or sql authentication. I tried using many different connections strings for the domain database, including using the connection string generated by (successfully) adding the server as a DataSource. What am I doing wrong?
EDIT: When I add the server in the server explorer of visual studio, I can connect successfully. I would assume that the connection string thereby generated is valid:
Data Source=mySubDomain.myDomain.local;Initial Catalog=myDatabase;Persist Security Info=True;User ID=myUser;Password=myPassword;
I checked and remote connections are allowed. I do not have permission to access the windows server which the sql server is running on, so I can't check any further settings.
EDIT 2: The following message comes with the exception:
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)
EDIT 3:
I tested my application on a different computer in the same domain, and it worked. Does someone have a clue what's going on or how I could find out?
The Group Policy or firewall (or both, not sure) of this company domain make my .exe file (and any other .exe) behave in the following way:
Launching it from C:\Program Files (or C:\Program Files (x86)) as any user works fine
Launching it from anywhere else as a normal user is not allowed and fails
Launching it from anywhere else as a local admin will execute the application, but connections are blocked
I have a sqlconnection problem. i have perfectly connection to sql server when i m using sqldatasource.
but when i m try use SqlConnection object throw an exception.
string qstring = "Data Source=****;Initial Catalog=**;User ID=**;Password=**";
SqlConnection con = new SqlConnection(qstring);
con.Open(); (exception thrown here)
exception is : 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)
Sql server is in different machine and i can connect using SqlDataSource object for example i can bind a grid by that way. But i must connect with SqlConnection object
Connection string is true because i have it from SqlDataSource...
Thx for your helps..
You might also want to make sure that the SQL Server is set up to accept remote connections.
(for sql2005 Configuration tools -> Surface AreaConfiguration-> Services and Connections -> database, Local and remote connections )
Is your SQL server is in the same machine ? if yes , Check the SQL server service is running , If its in a different machine,check your development machine has connectivity to it .You can ping to that machine to verify this. You can also check the surface area connection wizard to check whether the SQL server support remote connections , as snomag said
If the code that you have shown is what you have then I'm not surprised that you couldn't connect.
You'll need to have the correct Data Source, UserID and Password in qstring. As it stands asterisk characters won't mean anything.
A new point
A further point, which is often forgotten, SQLConnection will only work with Microsoft SQL Server. If your SQL is provided by a different manufacturer the use OleDBConnection instead.
I've got an C# .Net 3.5 executable that runs on a local machine and makes database calls to a server running SQL Server 2005. I've added a System DSN using the Data Sources manager on the local machine called "localserver" (with the driver set to SQL Server). When I create the DSN, I can test the connection to the server successfully.
I've added localserver to my connection string in my executable, and I get an 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)"
The server I am connecting to does allow for remote connections. When I replace localserver with the server name, it connects fine, but this program will be at multiple locations with multiple server names, so I need to make the data source dynamic.
Any ideas as to why this is happening?
Thank you,
Aaron
EDIT:
I've also tried using "localserver,1433" as my data source, but 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: TCP Provider, error: 0 - No such host is known.)"
EDIT:
Thank you for your responses. To solve my problem, I made a small method to gather the servername using an odbc connection.
I can then send the servername to the SqlConnection. Thanks again for your input.
SqlClient (ie. SqlConnection) has absolutely nothing to do with ODBC. As such using an ODBC Data source Name in the SqlClient connection string will get you nowhere fast.
You can configure the server name in app.config and build the connection string using SqlConnectionStringBuilder. At deployment, you change the exe's or the user's .config file appropriately.
As Remus said, DSN has nothing to do with SqlConnection. Instead use this connection string:
http://www.connectionstrings.com/sql-server-2005#1
Also read this:
http://msdn.microsoft.com/en-us/library/system.data.sqlclient.sqlconnection.connectionstring.aspx
An Excerpt from the above post:
To connect to a local computer,
specify "(local)" for the server. If a
server name is not specified, a
connection will be attempted to the
default instance on the local
computer.
I would repeat that SqlConnection has nothing to do with DSN,
I am using VSTS 2008 + .Net 3.5 + C# + SQL Server 2008 Enterprise on Windows Server 2003. I am using the following connection string, and labtest1 is the local machine name and I connect from local machine using ADO.Net. Then it always fail with connection error. But when I change in the connection string from "labtest1" to ".", connection has no issue with the same ADO.Net client code. Any ideas what is wrong?
Data Source=labtest1;Initial Catalog=CustomerDB;Trusted_Connection=true;Asynchronous Processing=true
Here is the detailed error message I got,
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: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server)
Looks like a Sql Server configuration issue to me : have you tried to tune protocols in Sql Server Network configuration ? Named Pipes or TCP/IP should be enabled.
When you use "." or "(local)" it connects to the default instance on your PC, perhaps the SQL Server was installed with instances, in which case you have to specify the instance name in the connection string in the format "SERVER\INSTANCE_NAME".
In SQL Management studio execute this query to see your full server\instance name
select ##servername
I have seen this issue previously with ZoneAlarms blocking the connection (on the machine trying to connect to the SQL server). I would spend some time investigating this area around firewalls etc.
Hope this helps
Do you have the Named Pipes network protocol enabled in the network config? (In the SQL Server Configuration Manager - sql server 2005, that's what I have, might be different in 2008 - you should be able to verify this setting)
Try to ping by the computer name: ping labtest1. if it does not find the server, then try ping labtest1.mydomainname.com with the domain name. If this works, then you just need to add/fix the DSN aliases in the domain controller or just re-login to the machine.
One other thins - and may not be relevant - but you've not specified the security model, at least not in the string provided as a sample.
I would expect to see: Integrated Security=True (given that its the local machine) in the connection string.
The other thing that may be relevant is - as has already been mentioned - the protocols, I'd look to make sure that TCP/IP is enabled.