Types of SQL statements swallowed by PG's engine

 I wonder if they exist and from where could you get a copy of the
list of Types of SQL statements that PG's engine would digest

 I think there should be such a list which I would use to model
hierarchical data structures for each of the complaint statements

 Say you have a statement like:

 SELECT USERS, PHONE WHERE ST='NY' AND PHONE NOT NULL;

 For example, this very basic statement could translate to a DS in
Java looking like the following:

// __
 class _2a{
  public String a00;
  public String a02;
 }

// __
 class DS00{
  public String St;
  public IsPhoneNull IsPh;
  public ArrayList<_2a> AL_2a;
// __
  DS00(){ AL_2a = new ArrayList<_2a>(); }
 }// DS00


// __
 Then your could would look like:

 DS00 DS = new DS00();
 DS.St = "NY";
 DS.IsPhoneNull = false;

 _2a a2 = new _2a();
 a2.a00 = "Jones";
 a2.a02 = "(213) 456-3345";
 AL_2a.add(a2);
 . . .

 This DS would just be a hierarchical object graph

 Of course things get complicated when you have such things as joins
and nested queries, I just gave you a complete example for you to see
exactly what I mean

 Do you know of any similar project in Java (, ANSI C or CPP)?

 Where could I get such a list?

 Are there data samples for stress testing PG tables?

 Thanks
 lbrtchx