I'm inserting new records into a MYSQL database using Perl DBI.  There
are four{*filter*} fields, each one of which has its corresponding variable in
my program.  I want to execute the "bind_param" method for each one of
them.  If you're not familiar with DBI here's an example of what I might
code:
   $sth->bind_param( 1, $message_id );
   $sth->bind_param( 2, $from_name );
   ...
   $sth->bind_param( 14, $body );

Ugly.  So I have a list of those variable names, thus

and I have a loop with a counter, like this
   for ( my $i = 1; $i<=14; $i++ ) {
       eval{ $ins_sth->bind_param( $i, $variable_name_list[$i-1] ) };
   }

... but the database is filling up with fields containing the literal
name of my variables:

   mysql> SELECT message_id FROM mailitem;
   +-------------+
   | message_id  |
   +-------------+
   | $message_id |
   +-------------+

I know that it's to do with when the variable name "becomes" the
variable value, but I've tried multiple combinations of $, \$, and
nested 'eval' and can't hit it.  Can someone help me work out how to do
this?  Yes, I could have coded four{*filter*} statements and had it working by
now, but it's a matter of elegance!

--

Heres a more fancy example that binds columns to the values inside a
hash (thanks to H.Merijn Brand):

              $sth->execute;
              my %row;

              while ($sth->fetch) {
                  print "$row{region}: $row{sales}\n";
              }

Let it inspire you to do your bind_params properly.

   for ( my $i = 1; $i<=$field_count; $i++ ) {
       $ins_sth->bind_param( $i, eval($variable_name_list[$i-1]));
   }

The "bind_param" method simply wants a value.

--

I would use the actual column names as keys, or use an id2name hash if
needed.

You won't need it anymore in a proper solution, but remember that you
can write
   for ( my $i = 1; $i<=$field_count; $i++ )
as
   for my $i ( 1 .. $field_count )

Let's try and avoid that...

:-)

        my %myvars;

--

  >> Whenever you feel the urge to use a string as a variable name you should
  >> seriously consider using a hash instead.

  HL> Jrgen, Tad and the Doctor all on my case ... I stand corrected and
  HL> will re-write it at once.  Thank you all.

add me to that list. using a hash is always better than symrefs. my rule
is only use symrefs when you want to mung the symbol table. never use it
for data structures. a hash is meant for data and is actually faster
than symrefs as it doesn't do all the symbol table stuff that symrefs
need.

uri

   Due to the use of single quotes '', the perl variables don't get
the values of the variables. Example:

my $string = "Hello";

print '$string'; # this would print $string on the console/tty.
print "$string"; #this would print Hello on the console/tty.

Is that what you are looking at? Let me know if I mis-interpreted the
question.

--
Krishna