new idea - Mailing list pgsql-sql

Let me know your opinion about next way of processing and extracting data.
This would very comfortable for delivery xml-data into any program, for example into browser.
Has this idea future ? What are you think ?

1. For exaple, you create SET:

create table a ( id   num      primary key; data float;
);
create table b ( id   num      primary key; ref  num      references a(id); data float;
);
create table c ( id   num      primary key; link num      references b(id); data float;
);
insert into a values (1,     12.3);
insert into b values (10, 1, 23.4);
insert into b values (20, 1, 34.5);
insert into b values (30, 1, 45.6);
insert into c values (100,10,56.7);
insert into c values (101,10,67.8);
insert into c values (200,20,78.9);
insert into c values (201,20,89.1);
insert into c values (300,30,91.2);

Request "a.b.c" (of Tree Manipulation Language :) ) will return the following
(term "SET" means, that first table in request is parental table,
next table is branch table)

<a     id=1   data=12.3> <b   id=10  data=23.4>   <c id=100 data=56.7/>   <c id=101 data=67.8/> </b> <b   id=20
data=34.5>  <c id=200 data=78.9/>   <c id=201 data=89.1/> </b> <b   id=30  data=45.6>   <c id=200 data=91.2/> </b>
 
</a>

2. For exaple, you create RELAY-RACE:

create table a ( id   num      primary key; ref  num      references b(id); data float;
);
create table b ( id   num      primary key; link num      references c(id); data float;
);
create table c ( id   num      primary key; data float;
);
insert into с values (100,    34.5);
insert into b values (10, 100,23.4);
insert into a values (1,  10, 12.3);

Request "a.b.c" will return the following
(term "RELAY-RACE" means, that first table in request is branch table,
next table is parental table)

<a     id=1   data=12.3> <b   id=10  data=23.4>   <c id=100 data=34.5/> </b>
</a>

---

Let's consider more complicated cases.

1. complicated case for "set"

create table a ( id   num      primary key; data float;
);
create table b ( id   num      primary key; ref1 num      references a(id); ref2 num      references a(id); data
float;
);
create table c ( id   num      primary key; lnk1 num      references b(id); lnk2 num      references b(id); data
float;
);
insert into a values (1,        12.3);
insert into a values (2,        23.4);
insert into b values (10, 1, 2, 34.5);
insert into b values (20, 1, 2, 45.6);
insert into b values (30, 1, 2, 56.7);
insert into b values (40, 1, 2, 67.8);
insert into c values (100,10,20,78.9);
insert into c values (101,10,20,89.1);
insert into c values (200,30,40,91.2);
insert into c values (201,30,40,88.8);

Request "a.b/ref1.c/lnk1" will return the following

<a     id=1           data=12.3> <b   id=10  ref2=2  data=34.5>   <c id=100 lnk2=20 data=78.9/>   <c id=101 lnk2=20
data=89.1/></b> <b   id=30  ref2=2  data=56.7>   <c id=200 lnk2=40 data=91.2/>   <c id=201 lnk2=40 data=88.8/> </b>
 
</a>

2. complicated case for "relay-race"

create table a ( id   num      primary key; ref1 num      references b(id); ref2 num      references b(id); data
float;
);
create table b ( id   num      primary key; lnk1 num      references c(id); lnk2 num      references c(id); data
float;
);
create table c ( id   num      primary key; data float;
);
insert into с values (201,        78.9);
insert into с values (200,        67.8);
insert into с values (101,        56.7);
insert into с values (100,        45.6);
insert into b values (20, 200,201,34.5);
insert into b values (10, 100,101,23.4);
insert into a values (1,  10, 20, 12.3);

Request "a/ref1.b/lnk1.c" will return the following

<a     id=1   data=12.3> <b   id=10  data=23.4>   <c id=100 data=45.6/> </b>
</a>