Quem estiver a programar Windows Form em C# e quiser aceder a uma Base de Dados MS Sql, pode dar uma vista de olhos a este código, espero que ajude.

string connectionString = "Data Source=.\\SQLEXPRESS;AttachDbFilename=D:\\Visual Studio 2008\\Projects\\testedb\\testedb\\Database1.mdf;Integrated Security=True; Connect Timeout=30;User Instance=True";

private static void CreateCommand(string connectionString)
{
using (SqlConnection connection = new SqlConnection(connectionString))
{
using (SqlCommand command =connection.CreateCommand())
{
SqlTransaction transaction = null;

try
{
// BeginTransaction() Requires Open Connection
connection.Open();

transaction = connection.BeginTransaction();

// Assign Transaction to Command
command.Transaction = transaction;

// Execute 1st Command
command.CommandText = “insert into pessoas values(’miguel’);”;
command.ExecuteNonQuery();

transaction.Commit();
}
catch
{
transaction.Rollback();
throw;
}
finally
{
connection.Close();
}
}
}