In non-procedural languages, what determines how this should be done?

Question

If you are comparing C vs SQL, this is an argument:

Unlike procedural languages ​​such as C, which describe how things should be done, SQL is non-procedural and describes what needs to be done.

So, the part for both languages ​​such as SQL is determined by the language itself, isn't it? What if I want to change the way a request works. Suppose I want to change the way SELECT is processed. Is it possible?

Answer 1

So, how is part of languages ​​such as SQL defined by the language itself?

( SQL), . , , - .

, SELECT . ?

- , . :

• , ,
• - http://en.wikipedia.org/wiki/Hint_%28SQL%29

, , , , - .

, , , , , , SQL. ( , SQL.)

Answer 2

. , , , - , . , , , / , . SQL , , ( ), ..

C, ( - ) ( - ODBC). , , , , (, , , , C , , - - , , ).

: , - . SQL , , "" "".