Dear Merline Martina,
Here is a sample code which explains about the database transactions in a
web service.

[Web Method]
public string adduser( string UserName, string UserPassword)
{
    string uname,upassword;
    uname=UserNmae;
    upassword=userPassword;
    string mycon=”Intial Catalog=test;Data Source= johnpaul\DBTEST; Integrated
security =SSPI”;

    //declare a sql connection by building a object named myconnection
    SqlConnection mysqlConnection =new SqlConnection(mycon);
    // declare sql command by using a object named mycommand
    SqlCommand mysqlCommand = new SqlCommand();
    // using sql transaction class
    SqlTransaction myTrans;

    // Open the connection.
    mysqlConnection.Open();
    // Assign the connection property.
    mysqlCommand.Connection = mysqlConnection;

    // Begin the transaction.
    myTrans = myConnection.BeginTransaction();

    // Assign transaction object for a pending local transaction
    mysqlCommand.Transaction = myTrans;
   
    try
    {
        // Insert the user record.
        mysqlCommand.CommandText = "Insert into useraccount VALUES
('"+uname+"','"+ufamily+"')";
        mysqlCommand.ExecuteNonQuery();
        // pass the data .transaction complete
        myTrans.Commit();
        return "transaction completed";
    }
    catch(Exception e)
    {
        // transaction cancel
        myTrans.Rollback();
        return e.ToString()+"transaction abort";
    }

}

Rgds,
John Paul. A