Some more code, as requested:

Retrieving the values (@grid is an array of array references retrieved from a mysql database with DBI). They are returned by reference and stuck in %dbdata:

   my %data = (
      balance   => $grid[0][0],
      overdraft => $grid[0][1],
      status    => uc($grid[0][2]),
   );
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The following is part of a subroutine that is passed a bunch of parameters and then:

   my %data = @_;

   my $amount  = $data{amount}   ? $data{amount}  : undef;
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Then the test:

unless( $dbdata{balance}+$dbdata{overdraft} >= $amount ){
      MyModule::Logger::log(BANK_ACCOUNT => "Debit FAILED user($self->
+{USER_ID}) reason($reason) amount($amount) because this failed: balan
+ce($dbdata{balance})+overdraft($dbdata{overdraft})>=amount($amount)")
+;
      return 0;
   }
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Example output:

Debit FAILED user(<removed>) reason(ORDER_PAYMENT) amount(1742) becaus
+e this failed: balance(1742)+overdraft(0)>=amount(1742)
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