How does this SQL query work?

Question

SQL

Hello everybody.
A long time ago I wrote a request, now I remembered it and I want to finally understand how it works.
Let there be 3 tables, two are connected through one.
table A ( id1, text1)
table B (id2, text2)
table C (id1, id2)
The query itself

select 
(select text1 from A where A.id1 = C.id1) as 'A',
(select text2 from B where B.id2= C.id2) as 'B'
from C;

How do subqueries know about table C?

Answer 1

the main query is table C. it is the number of records in it that will be displayed in the selection. and columns text1 and text2 are pulled out from subqueries to tables B and A. And those, in turn, will take values ​​for searching from the main query, that is, from table C.

Answer 2

According to SQL-92
1. FROM is executed - a work table is formed
2. WHERE clause predicates are applied to this result
3. GROUP By
4. HAVING
5. SELECT
6. ORDER BY (not formally part of the SELECT definition)
(C) Joe Celko. SQL for professionals. Programming.