asp.net DataList linkage level two menu binding data

This example is about the use of DataList data-bound controls, because I was just learning this dongdong, so there is a wrong place to ask you advice ah.
ASP tutorial. NET code

private void Dataload ()

{

DataSet ds = new DataSet ();

String sql = "SELECT * from Partent";

SqlConnection con = new SqlConnection ("Data source=pc-200912151837;initial catalog=test;integrated security=true");

SqlDataAdapter da = new SqlDataAdapter (sql, con);

Da.fill (ds, "Xinghao");
String sql2 = "SELECT * from parent";

SqlDataAdapter da2 = new SqlDataAdapter (Sql2, con);

Da2.fill (ds, "parent");

That's the key, it seems, to create a relationship between 2 tables by ID, and then load the data
Ds.relations.add ("Myreation", ds.tables["son"].columns["son_id"], ds.tables["parent"].columns["parent_id"]);

Datalist.datasource = ds.tables["Son"].defaultview;

Datalist.databind ();

}

Database Tutorial Code:

　　

CREATE table partent

(      partent_id int not null primary key, Primary key id     

Partent_name varchar () NOT NULL

)

  Create Table son

(

son_id ID NOT null primary key, primary key tid    

  So N_name varchar null,    

  partent_id not null  //partent associated with id

)