SQL Server 2008 connection strings

Microsoft SqlClient Data Provider for SQL Server

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;

Why is the Database parameter needed? If the named database have already been attached, SQL Server does not reattach it. It uses the attached database as the default for the connection.

Database mirroring

If you connect with ADO.NET or the SQL Native Client to a database that is being mirrored, your application can take advantage of the drivers ability to automatically redirect connections when a database mirroring failover occurs. You must specify the initial principal server and database in the connection string and the failover partner server.

Data Source=myServerAddress;Failover Partner=myMirrorServerAddress;Initial Catalog=myDataBase;Integrated Security=True;

There is ofcourse many other ways to write the connection string using database mirroring, this is just one example pointing out the failover functionality. You can combine this with the other connection strings options available.

Using an User Instance on a local SQL Server Express instance

The User Instance functionality creates a new SQL Server instance on the fly during connect. This works only on a local SQL Server instance and only when connecting using windows authentication over local named pipes. The purpose is to be able to create a full rights SQL Server instance to a user with limited administrative rights on the computer.

Data Source=.\SQLExpress;Integrated Security=true;AttachDbFilename=C:\MyFolder\MyDataFile.mdf;User Instance=true;

To use the User Instance functionality you need to enable it on the SQL Server. This is done by executing the following command: sp_configure 'user instances enabled', '1'. To disable the functionality execute sp_configure 'user instances enabled', '0'.

Specifying packet size

Server=myServerAddress;Database=myDataBase;User ID=myUsername;Password=myPassword;Trusted_Connection=False;Packet Size=4096;

By default, the Microsoft .NET Framework Data Provider for SQL Server sets the network packet size to 8192 bytes. This might however not be optimal, try to set this value to 4096 instead. The default value of 8192 might cause Failed to reserve contiguous memory errors as well, read more here.

.NET Framework Data Provider for SQL Server

Trusted Connection from a CE device

A Windows CE device is most often not authenticated and logged in to a domain but it is possible to use SSPI or trusted connection and authentication from a CE device using this connection string.

Data Source=myServerAddress;Initial Catalog=myDataBase;Integrated Security=SSPI;User ID=myDomain\myUsername;Password=myPassword;

Note that this will only work on a CE device.

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;

Why is the Database parameter needed? If the named database have already been attached, SQL Server does not reattach it. It uses the attached database as the default for the connection.

Database mirroring

If you connect with ADO.NET or the SQL Native Client to a database that is being mirrored, your application can take advantage of the drivers ability to automatically redirect connections when a database mirroring failover occurs. You must specify the initial principal server and database in the connection string and the failover partner server.

Data Source=myServerAddress;Failover Partner=myMirrorServerAddress;Initial Catalog=myDataBase;Integrated Security=True;

There is ofcourse many other ways to write the connection string using database mirroring, this is just one example pointing out the failover functionality. You can combine this with the other connection strings options available.

Using an User Instance on a local SQL Server Express instance

The User Instance functionality creates a new SQL Server instance on the fly during connect. This works only on a local SQL Server instance and only when connecting using windows authentication over local named pipes. The purpose is to be able to create a full rights SQL Server instance to a user with limited administrative rights on the computer.

Data Source=.\SQLExpress;Integrated Security=true;AttachDbFilename=C:\MyFolder\MyDataFile.mdf;User Instance=true;

To use the User Instance functionality you need to enable it on the SQL Server. This is done by executing the following command: sp_configure 'user instances enabled', '1'. To disable the functionality execute sp_configure 'user instances enabled', '0'.

Specifying packet size

Server=myServerAddress;Database=myDataBase;User ID=myUsername;Password=myPassword;Trusted_Connection=False;Packet Size=4096;

By default, the Microsoft .NET Framework Data Provider for SQL Server sets the network packet size to 8192 bytes. This might however not be optimal, try to set this value to 4096 instead. The default value of 8192 might cause Failed to reserve contiguous memory errors as well, read more here.

SQL Server Native Client 11.0 OLE DB Provider

Using a non-standard port

If your SQL Server listens on a non-default port you can specify that using the servername,xxxx syntax (note the comma, it's not a colon).

Provider=SQLNCLI11;Server=myServerName,myPortNumber;Database=myDataBase;Uid=myUsername;Pwd=myPassword;

The default SQL Server port is 1433 and there is no need to specify that in the connection string.

Database mirroring

If you connect with ADO.NET or the SQL Native Client to a database that is being mirrored, your application can take advantage of the drivers ability to automatically redirect connections when a database mirroring failover occurs. You must specify the initial principal server and database in the connection string and the failover partner server.

Provider=SQLNCLI11;Data Source=myServerAddress;Failover Partner=myMirrorServerAddress;Initial Catalog=myDataBase;Integrated Security=True;

There is ofcourse many other ways to write the connection string using database mirroring, this is just one example pointing out the failover functionality. You can combine this with the other connection strings options available.

SQL Server Native Client 10.0 OLE DB Provider

Using a non-standard port

If your SQL Server listens on a non-default port you can specify that using the servername,xxxx syntax (note the comma, it's not a colon).

Provider=SQLNCLI10;Server=myServerName,myPortNumber;Database=myDataBase;Uid=myUsername;Pwd=myPassword;

The default SQL Server port is 1433 and there is no need to specify that in the connection string.

Database mirroring

If you connect with ADO.NET or the SQL Native Client to a database that is being mirrored, your application can take advantage of the drivers ability to automatically redirect connections when a database mirroring failover occurs. You must specify the initial principal server and database in the connection string and the failover partner server.

Provider=SQLNCLI10;Data Source=myServerAddress;Failover Partner=myMirrorServerAddress;Initial Catalog=myDataBase;Integrated Security=True;

There is ofcourse many other ways to write the connection string using database mirroring, this is just one example pointing out the failover functionality. You can combine this with the other connection strings options available.

Microsoft ODBC Driver 17 for SQL Server

Database mirroring

If you connect to a database that is being mirrored, your application can take advantage of the drivers ability to automatically redirect connections when a database mirroring failover occurs. You must specify the initial principal server and database in the connection string and the failover partner server.

Driver={ODBC Driver 17 for SQL Server};Server=myServerAddress;Failover_Partner=myMirrorServerAddress;Database=myDataBase;Trusted_Connection=yes;

This one is working only on Windows, not on macOS or Linux. There is ofcourse many other ways to write the connection string using database mirroring, this is just one example pointing out the failover functionality. You can combine this with the other connection strings options available.

Please note if you are using TCP/IP (using the network library parameter) and database mirroring, including port number in the address (formed as servername,portnumber) for both the main server and the failover partner can solve some reported issues.

Microsoft ODBC Driver 13 for SQL Server

Database mirroring

If you connect to a database that is being mirrored, your application can take advantage of the drivers ability to automatically redirect connections when a database mirroring failover occurs. You must specify the initial principal server and database in the connection string and the failover partner server.

Driver={ODBC Driver 13 for SQL Server};Server=myServerAddress;Failover_Partner=myMirrorServerAddress;Database=myDataBase;Trusted_Connection=yes;

This one is working only on Windows, not on macOS or Linux. There is ofcourse many other ways to write the connection string using database mirroring, this is just one example pointing out the failover functionality. You can combine this with the other connection strings options available.

Please note if you are using TCP/IP (using the network library parameter) and database mirroring, including port number in the address (formed as servername,portnumber) for both the main server and the failover partner can solve some reported issues.

Microsoft ODBC Driver 11 for SQL Server

Using a non-standard port

If your SQL Server listens on a non-default port you can specify that using the servername,xxxx syntax (note the comma, it's not a colon).

Driver={ODBC Driver 11 for SQL Server};Server=myServerName,myPortNumber;Database=myDataBase;UID=myUsername;PWD=myPassword;

The default SQL Server port is 1433 and there is no need to specify that in the connection string.

Database mirroring

If you connect to a database that is being mirrored, your application can take advantage of the drivers ability to automatically redirect connections when a database mirroring failover occurs. You must specify the initial principal server and database in the connection string and the failover partner server.

Driver={ODBC Driver 11 for SQL Server};Server=myServerAddress;Failover_Partner=myMirrorServerAddress;Database=myDataBase;Trusted_Connection=yes;

This one is working only on Windows, not on macOS or Linux. There is ofcourse many other ways to write the connection string using database mirroring, this is just one example pointing out the failover functionality. You can combine this with the other connection strings options available.

Please note if you are using TCP/IP (using the network library parameter) and database mirroring, including port number in the address (formed as servername,portnumber) for both the main server and the failover partner can solve some reported issues.

SQL Server Native Client 11.0 ODBC Driver

Using a non-standard port

If your SQL Server listens on a non-default port you can specify that using the servername,xxxx syntax (note the comma, it's not a colon).

Driver={SQL Server Native Client 11.0};Server=myServerName,myPortNumber;Database=myDataBase;Uid=myUsername;Pwd=myPassword;

The default SQL Server port is 1433 and there is no need to specify that in the connection string.

Prompt for username and password

This one is a bit tricky. First you need to set the connection object's Prompt property to adPromptAlways. Then use the connection string to connect to the database.

oConn.Properties("Prompt") = adPromptAlways

oConn.Open "Driver={SQL Server Native Client 11.0};Server=myServerAddress;Database=myDataBase;"

Database mirroring

If you connect with ADO.NET or the SQL Native Client to a database that is being mirrored, your application can take advantage of the drivers ability to automatically redirect connections when a database mirroring failover occurs. You must specify the initial principal server and database in the connection string and the failover partner server.

Driver={SQL Server Native Client 11.0};Server=myServerAddress;Failover_Partner=myMirrorServerAddress;Database=myDataBase;Trusted_Connection=yes;

There is ofcourse many other ways to write the connection string using database mirroring, this is just one example pointing out the failover functionality. You can combine this with the other connection strings options available.

Please note if you are using TCP/IP (using the network library parameter) and database mirroring, including port number in the address (formed as servername,portnumber) for both the main server and the failover partner can solve some reported issues.

SQL Server Native Client 10.0 ODBC Driver

Using a non-standard port

If your SQL Server listens on a non-default port you can specify that using the servername,xxxx syntax (note the comma, it's not a colon).

Driver={SQL Server Native Client 10.0};Server=myServerName,myPortNumber;Database=myDataBase;Uid=myUsername;Pwd=myPassword;

The default SQL Server port is 1433 and there is no need to specify that in the connection string.

Database mirroring

If you connect with ADO.NET or the SQL Native Client to a database that is being mirrored, your application can take advantage of the drivers ability to automatically redirect connections when a database mirroring failover occurs. You must specify the initial principal server and database in the connection string and the failover partner server.

Driver={SQL Server Native Client 10.0};Server=myServerAddress;Failover_Partner=myMirrorServerAddress;Database=myDataBase;Trusted_Connection=yes;

There is ofcourse many other ways to write the connection string using database mirroring, this is just one example pointing out the failover functionality. You can combine this with the other connection strings options available.

Please note if you are using TCP/IP (using the network library parameter) and database mirroring, including port number in the address (formed as servername,portnumber) for both the main server and the failover partner can solve some reported issues.

Context Connection

Context Connection

Connecting to "self" from within your CLR stored prodedure/function. The context connection lets you execute Transact-SQL statements in the same context (connection) that your code was invoked in the first place.

C#
 using(SqlConnection connection = new SqlConnection("context connection=true"))
 {
     connection.Open();
     // Use the connection
 }

VB.Net
 Using connection as new SqlConnection("context connection=true")
     connection.Open()
     ' Use the connection
 End Using