SQL Server Connection String in ADO.NET

Somebody asked me all members used in ADO.NET connection string.
Reference: MSDN

The ConnectionString property of SqlConnection represents a connection string. You can use the ConnectionString property to connect to a database.

Here is an example of Connection String for SQL Server.

"Persist Security Info=False;Integrated Security=true;Initial Catalog=Northwind;server=(local)"


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.

The basic format of a connection string includes a series of keyword/value pairs separated by semicolons. The equal sign (=) connects each keyword and its value. The following table lists the valid names for keyword values within the ConnectionString.




Application Name


The name of the application, or '.NET SQLClient Data Provider' if no application name is provided.



When true, enables asynchronous operation support. Recognized values are true, false, yes, and no.



extended properties


Initial File Name


The name of the primary database file, including the full path name of an attachable database. AttachDBFilename is only supported for primary data files with an .mdf extension.

The attachment will fail if the primary data file is read-only.

The path may be absolute or relative by using the DataDirectory substitution string. If DataDirectory is used, the database file must exist within a subdirectory of the directory pointed to by the substitution string.


Remote server, HTTP, and UNC path names are not supported.

The database name must be specified with the keyword 'database' (or one of its aliases) as in the following:

"AttachDbFileName=|DataDirectory|\data\YourDB.mdf;integrated security=true;database=YourDatabase"

An error will be generated if a log file exists in the same directory as the data file and the 'database' keyword is used when attaching the primary data file. In this case, remove the log file. Once the database is attached, a new log file will be automatically generated based on the physical path.

Connect Timeout


Connection Timeout


The length of time (in seconds) to wait for a connection to the server before terminating the attempt and generating an error.

Context Connection


true if an in-process connection to SQL Server should be made.

Current Language


The SQL Server Language record name.

Data Source








Network Address


The name or network address of the instance of SQL Server to which to connect. The port number can be specified after the server name:

server=tcp:servername, portnumber

When specifying a local instance, always use (local). To force a protocol, add one of the following prefixes:

np:(local), tcp:(local), lpc:(local)


ADO.NET 2.0 does not support asynchronous commands over shared memory for SQL Server 2000 or earlier. However, you can force the use of TCP instead of shared memory, either by prefixing tcp: to the server name in the connection string, or by using localhost.



When true, SQL Server uses SSL encryption for all data sent between the client and server if the server has a certificate installed. Recognized values are true, false, yes, and no.



true indicates that the SQL Server connection pooler automatically enlists the connection in the creation thread's current transaction context.

Failover Partner


The name of the failover partner server where database mirroring is configured.

The Failover Partner keyword is not supported by .NET Framework version 1.0 or 1.1.

Initial Catalog




The name of the database.

Integrated Security




When false, User ID and Password are specified in the connection. When true, the current Windows account credentials are used for authentication.

Recognized values are true, false, yes, no, and sspi (strongly recommended), which is equivalent to true.

If User ID and Password are specified and Integrated Security is set to true, the User ID and Password will be ignored and Integrated Security will be used.



When true, an application can maintain multiple active result sets (MARS). When false, an application must process or cancel all result sets from one batch before it can execute any other batch on that connection.

Recognized values are true and false.

The keyword is not supported by .NET Framework version 1.0 or 1.1.

Network Library




The network library used to establish a connection to an instance of SQL Server. Supported values include:

dbnmpntw (Named Pipes)

dbmsrpcn (Multiprotocol, Windows RPC)

dbmsadsn (Apple Talk)

dbmsgnet (VIA)

dbmslpcn (Shared Memory)

dbmsspxn (IPX/SPX)

dbmssocn (TCP/IP)

Dbmsvinn (Banyan Vines)

The corresponding network DLL must be installed on the system to which you connect. If you do not specify a network and you use a local server (for example, "." or "(local)"), shared memory is used. In this example, the network library is Win32 Winsock TCP/IP (dbmssocn), and 1433 is the port being used.

Network Library=dbmssocn;Data Source=,1433;

Packet Size


Size in bytes of the network packets used to communicate with an instance of SQL Server.





The password for the SQL Server account logging on. Not recommended. To maintain a high level of security, we strongly recommend that you use the Integrated Security or Trusted_Connection keyword instead.

Persist Security Info


When set to false or no (strongly recommended), security-sensitive information, such as the password, is not returned as part of the connection if the connection is open or has ever been in an open state. Resetting the connection string resets all connection string values including the password. Recognized values are true, false, yes, and no.



true if replication is supported using the connection.

Transaction Binding

Implicit Unbind

Controls connection association with an enlisted System.Transactions transaction.

Possible values are:

Transaction Binding=Implicit Unbind;

Transaction Binding=Explicit Unbind;

Implicit Unbind causes the connection to detach from the transaction when it ends. After detaching, additional requests on the connection are performed in autocommit mode. The System.Transactions.Transaction.Current property is not checked when executing requests while the transaction is active. After the transaction has ended, additional requests are performed in autocommit mode.

Explicit Unbind causes the connection to remain attached to the transaction until the connection is closed or an explicit SqlConnection.TransactionEnlist(null) is called. An InvalidOperationException is thrown if Transaction.Current is not the enlisted transaction or if the enlisted transaction is not active.



When set to true, SSL is used to encrypt the channel when bypassing walking the certificate chain to validate trust. If TrustServerCertificate is set to true and Encrypt is set to false, the channel is not encrypted. Recognized values are true, false, yes, and no. For more information, see Connection String Syntax (ADO.NET).

Type System Version


A string value that indicates the type system the application expects. Possible values are:

Type System Version=SQL Server 2000;

Type System Version=SQL Server 2005;

Type System Version=SQL Server 2008;

Type System Version=Latest;

When set to SQL Server 2000, the SQL Server 2000 type system is used. The following conversions are performed when connecting to a SQL Server 2005 instance:




When set to SQL Server 2005, the SQL Server 2005 type system is used. No conversions are made for the current version of ADO.NET.

When set to Latest, the latest version than this client-server pair can handle is used. This will automatically move forward as the client and server components are upgraded.

User ID


The SQL Server login account. Not recommended. To maintain a high level of security, we strongly recommend that you use the Integrated Security or Trusted_Connection keywords instead.

User Instance


A value that indicates whether to redirect the connection from the default SQL Server Express instance to a runtime-initiated instance running under the account of the caller.

Workstation ID

The local computer name

The name of the workstation connecting to SQL Server.


The following table lists the valid names for connection pooling values within the ConnectionString.




Connection Lifetime


When a connection is returned to the pool, its creation time is compared with the current time, and the connection is destroyed if that time span (in seconds) exceeds the value specified by Connection Lifetime. This is useful in clustered configurations to force load balancing between a running server and a server just brought online.

A value of zero (0) causes pooled connections to have the maximum connection timeout.



When true, the pooler automatically enlists the connection in the creation thread's current transaction context. Recognized values are true, false, yes, and no.

Load Balance Timeout


The minimum time, in seconds, for the connection to live in the connection pool before being destroyed.

Max Pool Size


The maximum number of connections allowed in the pool.

Min Pool Size


The minimum number of connections allowed in the pool.



When true, the SQLConnection object is drawn from the appropriate pool, or if it is required, is created and added to the appropriate pool. Recognized values are true, false, yes, and no.


Here is an example that creates a SqlConnection and sets the ConnectionString property before opening the connection.

private static void OpenSqlConnection()
    string connectionString = GetConnectionString();
    using (SqlConnection connection = new SqlConnection())
       connection.ConnectionString = connectionString;
        Console.WriteLine("State: {0}", connection.State);
        Console.WriteLine("ConnectionString: {0}",
static private string GetConnectionString()
return "Data Source=MSSQL1;Initial Catalog=AdventureWorks;"
        + "Integrated Security=true;";

Here is code in VB.NET.

Private Sub OpenSqlConnection()

    Dim connectionString As String = GetConnectionString()


    Using connection As New SqlConnection() 

        connection.ConnectionString = connectionString 


        Console.WriteLine("State: {0}", connection.State)

        Console.WriteLine("ConnectionString: {0}", _


    End Using

End Sub


Private Function GetConnectionString() As String

    ' To avoid storing the connection string in your code, 

    ' you can retrieve it from a configuration file.

    Return "Data Source=MSSQL1;Database=AdventureWorks;" _

      & "Integrated Security=true;"

End Function