Chess opening book

Frnds,what's the best book on chess openings with every openings mainline and sidelines ?

http://www.365chess.com/opening.php

this site is helpful

I think FCO (Fundamental Chess Openings by Paul van der Sterren) is the current 1 volume standard.   In many ways it's like Reuben Fine's The Ideas Behind The Chess Openings, but modernized and expanded.  With the availability of inexpensive (or totally free) databases, you don't need a book to feed you endless lines and variations; what you need is an explanation of the typical plans for each side and how those change.  You have to be seriously invested in an opening to need more than FCO but repertoire books are the next step.

Thank you guys. Bt baddogno sir, in an opening book,some explanations maybe given like which line of an sicilian:scheveningen is better than the other bt it's hard to find in databases.

Pfren sir, obviously tactics and endgames should be studied more than openings & tactics is everything, bt if my game started badly in the opening itself, then how I'll improve?

Analyse your own games on a board and try to find your first error in the opening, then correct it. Going so on until you get out of your openings with less to no errors and be ok in the middlegame, then its a matter of tactics, plans and endgame knowledge.

Birdmen sir,when analysing my own games on my own,i will still find a weak move -a good move until someone/engine corrected the move sequence.

yo