SqlConnection Constructor
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SqlConnection Constructor

Initializes a new instance of the SqlConnection class.

Namespace:  System.Data.SqlClient
Assembly:  System.Data (in System.Data.dll)

public SqlConnection()

When a new instance of SqlConnection is created, the read/write properties are set to the following initial values unless they are specifically set using their associated keywords in the ConnectionString property.


Initial value


empty string ("")




empty string ("")


empty string ("")

You can change the value for these properties only by using the ConnectionString property. The SqlConnectionStringBuilder class provides functionality for creating and managing the contents of connection strings.

The following example creates and opens a SqlConnection.

private static void OpenSqlConnection()
    string connectionString = GetConnectionString();
    using (SqlConnection connection = new SqlConnection(connectionString))
        Console.WriteLine("ServerVersion: {0}", connection.ServerVersion);
        Console.WriteLine("State: {0}", connection.State);

static private string GetConnectionString()
    // To avoid storing the connection string in your code, 
    // you can retrieve it from a configuration file, using the 
    // System.Configuration.ConfigurationSettings.AppSettings property 
    return "Data Source=(local);Initial Catalog=AdventureWorks;"
        + "Integrated Security=SSPI;";

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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