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DbConnectionStringBuilder.Add Method

Adds an entry with the specified key and value into the DbConnectionStringBuilder.

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

public void Add(
	string keyword,
	Object value


Type: System.String

The key to add to the DbConnectionStringBuilder.

Type: System.Object

The value for the specified key.


keyword is a null reference (Nothing in Visual Basic).


The DbConnectionStringBuilder is read-only.


The DbConnectionStringBuilder has a fixed size.

The Item property can also be used to add new elements by setting the value of a key that does not exist in the dictionary. For example: myCollection["myNonexistentKey"] = myValue.

Calling the Add method by passing a null (Nothing in Visual Basic) key throws an ArgumentNullException. However, calling the Add method by passing a null value removes the key/value pair.

The following example creates a new DbConnectionStringBuilder and adds items. The code also demonstrates overwriting an existing item using the Add method, and includes a commented block that would throw an ArgumentNullException.


This example includes a password to demonstrate how DbConnectionStringBuilder works with connection strings. In your applications, we recommend that you use Windows Authentication. If you must use a password, do not include a hard-coded password in your application.

static void Main()
        DbConnectionStringBuilder builder =
            new DbConnectionStringBuilder();
        builder.Add("Data Source", "ServerName");
        builder.Add("Initial Catalog", "TheDatabase");
        builder.Add("User ID", "UserName");
        builder.Add("Password", "*******");
        builder.Add("Command Logging", false);

        // Overwrite the existing "User ID" value.
        builder.Add("User ID", "NewUserName");

        // The following code would trigger  
        // an ArgumentNullException: 
        // builder.Add(null, "Some Value");

    catch (ArgumentNullException)
        Console.WriteLine("Null key values are not allowed.");

    Console.WriteLine("Press Enter to continue.");

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1
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