evaluating field from mySQL

shreedarasp has asked for the wisdom of the Perl Monks concerning the following question:

I have a unique requirement, in one of my MySql table i have a field called 'input_folder' and i have defined its value as '$ENV{INP_DIR}' and in my windows profile, i have defined this ENV variable and valu is set as "C:/tmp/setup". my idea is to read this field from SQL table and substitute to windows ENV variable. But when i read this from my perl script i get it as $ENV{INP_DIR} itself and NOT substituted to its true ENV value. is there a way to read the actual value? i tried with $t = $v->{input_folder}; $t2 = eval $t; but it returns just blank. i tried it with $t3 = "$t/xx" still did not work. any suggestion? thanks for replies, i have number of fields which has similar values. so i wanted it to work this way. However Corion's tips was usefull and workable. while doing experiment i found a way. In mySQL table i have modified the value from $ENV{INP_DIR} to "$ENV{INP_DIR}" double quotes included in value itself and it worked.

Comment on evaluating field from mySQL

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Re: evaluating field from mySQL by Corion (Patriarch) on Sep 15, 2011 at 06:57 UTC
How about extracting the string and then accessing `%ENV` with it? `my $db_str = '$ENV{INP_DIR}'; $db_str =~ s/\$ENV\{([^}]*)\}/$ENV{$1}/ge; print $db_str;` [download] Also see eval, but that will allow anybody to run arbitrary code.	[reply] [d/l] [select]
Re: evaluating field from mySQL by onelesd (Pilgrim) on Sep 15, 2011 at 07:04 UTC
Am I missing something? If you know the ENV variable you want is INP_DIR, why not just use it directly? `my $dir = $ENV{INP_DIR} ;`	[reply] [d/l]
Re: evaluating field from mySQL by Anonymous Monk on Sep 15, 2011 at 13:32 UTC
Be sure that you put this construction in double quotes not single ones. (Double-quotes cause interpolation; single-quotes suppress it.) And be sure also that you are sending the value (in an insert or update query) using a query-parameter.	[reply]
Re^2: evaluating field from mySQL by shreedarasp (Acolyte) on Sep 16, 2011 at 04:25 UTC
thanks for replies, i have number of fields which has similar values. so i wanted it to work this way. However Corion's tips was usefull and workable. while doing experiment i found a way. In mySQL table i have modified the value from $ENV{INP_DIR} to "$ENV{INP_DIR}" double quotes included in value itself and it worked.	[reply]