Capitalized Databases and columns names

ref : PHP5 and postgresql 8.1

Hello,

For reasons of lisibility I've created DataBases and
Table Columns with capitalized names.

To access databases in php code I just use double
cotes as delimiters for names in sql requests.

I compose on-demand requests with concatened
php strings. The result is for example :
select "TCRtimestp" from "TrcDFCR" where "TCRtimestp"=20060228113419 ;

Such requests are manageable thru concatenation
but I get problems with functions like
select nextval ('TCRnrordre') ;
where the request becomes select nextval ('trcnrordre') ;
where everything is in lowercase and the result is :
relation tcrnrordre does not exist.
select nextval ('"TCRnrordre"') ; is not possible due
to syntax error.

I just don't achieve nor in php nor in psql to get the
next value because of this capitalize problem.
Does someone know if there is a solution or if
I have to use only lowercase caracters ?

Thanks.

Nadine