Truncate Or Delete With CONSTRAINTS

Hi all
i have a problem.
i have this method


protected void DeleteDataFirstAccess()

{

SqlCommand cmd = new SqlCommand();

cmd.Connection = conn;

cmd.CommandText = "select name from sys.all_objects where type='U'";

DataTable table = DataBase.GetDatatable(cmd); //this is one of my method wich return a datatable with data

foreach (DataRow row in table.Rows)

{

SqlCommand cmd_delete = new SqlCommand();

cmd_delete.CommandText = "TRUNCATE TABLE " + row[0].ToString();

cmd_delete.Connection = conn;

cmd_delete.ExecuteNonQuery();

cmd_delete.Dispose();

}

cmd.Dispose();

}

when i run i have an error with some tables constraints.
As you know If we try to TRUNCATE a table, and the table is have a relationship with other table like for exemple Employees_Salary with the constraint of SQL Foreign Key then we can't TRUNCATE the table with SQL Truncate Table command, we need to TRUNCATE the Employees_Salary table first because Employees_Salary is depending on it and that is having some records. That's why we need to TRUNCATE both tables and the sequence is to empty that table which is based on SQL Foreign Key or remove this constraint first.

What i need is a list of all database tables ordered by the right sequence considering the constraints
Anyone can help me?

thanks in advance
bye
Marco