CREATE TYPE [dbo].[MyFriends] AS TABLE(
	[firstname] [varchar](50) NOT NULL,
	[lastname] [varchar](50) NOT NULL
)

 
CREATE TABLE [dbo].[friends](
	[friendID] [int] IDENTITY(1,1) NOT NULL,
	[firstname] [varchar](50) NOT NULL,
	[lastname] [varchar](50) NOT NULL,
 CONSTRAINT [PK_friends] PRIMARY KEY CLUSTERED 
(
	[friendID] ASC
)WITH (PAD_INDEX  = OFF, STATISTICS_NORECOMPUTE  = OFF, 
	IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS  = ON, 
	ALLOW_PAGE_LOCKS  = ON) ON [PRIMARY]
) ON [PRIMARY]

 
CREATE PROCEDURE [dbo].[addFriends]
	@friends MyFriends READONLY
AS
BEGIN
	INSERT INTO friends(firstname, lastname)
	SELECT firstname, lastname 
	FROM @friends
END

 
using (SqlConnection connection = new SqlConnection(@"Some connectionString"))
{
    using (SqlCommand command = new SqlCommand("addFriends", connection) { CommandType = CommandType.StoredProcedure })
    {
        DataTable dt = new DataTable();
 
		// Add columns
	dt.Columns.Add("firstname", typeof(String)).MaxLength = 50;
        dt.Columns.Add("lastname", typeof(String)).MaxLength = 50; ;
 
        // Add some rows
	dt.Rows.Add(new Object[] { "Eugene", "Stander" });
        dt.Rows.Add(new Object[] { "Roland", "Cooper" });
        dt.Rows.Add(new Object[] { "Jacques", "Brits" });
 
        connection.Open();		
        command.Parameters.Add("@friends", SqlDbType.Structured).Value = dt;
        command.ExecuteNonQuery();
    }
}