To all,

Thank you for your input. It is good to know that an 'alias' is possible, although I don't think I need it for my current problem.

I know it was the question I asked because I had hoped it would solve my problem. Nonetheless, I am happy to learn all new things.

My Problem:

I wanted an easy way to ensure that the order of a list of columns read from database query could be modified, without any mistakes.

I was worried that if someone changed the select statement, they might forget to change the statement that actually reads the data.

My hopeful solution... create a single list of columns that would be used to construct the query statement, and be used to parse the query result.

Condition to this hopeful solution... I still want to use 'use strict' because it will also prevent some muck-ups.

I think I have got it!. See below

#!/usr/bin/perl -w
# ------------------------------------------
# PURPOSE:
# - Test if I can make a program that reads
#   a db table.  
#   Maintainability issue: Want to be able to easily
#   manipulate the order in which the columns
#   are read.
#   
#   To change order of which columns are selected/read
#   from db only requires changing @parm_cols.
#
#   Robustness?  If a column is added to @parm_cols
#   without predefining the variable, use strict will 
#   complain if one tries to use that variable.?
#
# ------------------------------------------
use strict;
# ------------------
# define my variables
# ------------------
my      (
          $abc, $def, $ghi, $jkl
         );

my @parm_cols = ();
my $map_to_array;

# -----------------
# define columns and order to read them
# Note order of columns not same as the 
# my definition above.
# -----------------
@parm_cols =  qw(
                  abc ghi jkl def
                );

                    
# ---------------------
# define select statement
# ---------------------
my $select = 'SELECT '.join(",",@parm_cols);


# ---------------------
# define how to map array which
# is result of query statement to db
# to individual variables
# ---------------------
map {$_='$'.$_} (my @tmp = @parm_cols);
$map_to_array = join (",",@tmp);

# ---------------------
# read db (for testing purpose, just set array)
# ---------------------
my @array = (4,3,2,1);

# ---------------------
# populate my already declared
# variables
# ---------------------
eval "($map_to_array) = ".'@array';

# ---------------------
# test to see if it works
# ---------------------
print "$abc $def $ghi $jkl\n";

exit;
[download]

Thanks again,

Sandy

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