techniques in molecular biology - a useful book needed (Oct/13/2007 )

i need a useful book which will clarify each step in a molecular biology technique..
techniques like,

DNA extraction.
PCR (real-time,..etc)
RFLP
Gel electrophoresis (commet assay,..etc)
nouthern,southern,western blot
.
.
.
etc

why a substance is added,,and so on...
and a trouble-shooting section

am i dreaming ?? or there is such book
i searched alot without any reverts ...

Have you checked "Molecular Cloning: A Laboratory Manual"?

thanks alot scolix for ur fast reply
i'll check it