#!/usr/bin/perl -w

use DBI; 

#### Make a database connection
eval {
    $MY_CONNECTION = DBI->connect("$SERVER", "$UID", "$PWD", {PrintError => 0}) or die "Cannot connect: $DBI::errstr\n";
};

if ($@) {
    print "ERROR: Database issue.  The error was: $@";
    exit(2);
}

#### Get the data
my $GET_DB_DATA = $MY_CONNECTION->prepare("SELECT Field_1, Field_2, Field_3 " .
                                          "FROM " . $TableName . " " . 
                                          "WHERE Field_4 = 'foo' ");

eval {
    $GET_DB_DATA->execute() or die "Database issue. $DBI::errstr\n";
};

if ($@) {
    print "ERROR: Cannot get table data.  The error was: $@";
    exit(2);
}
else {
    while ( my @RETURNED_DATA_ARRAY = $GET_DB_DATA->fetchrow ) {
        if ( $RETURNED_DATA_ARRAY[0] ne $RETURNED_DATA_ARRAY[1] ) {

            #### Update the table data
            my $UPDATE_TABLE = $MY_CONNECTION->prepare("UPDATE " . $TableName . " " .
                                                       "SET Field_2 = '" . $RETURNED_DATA_ARRAY[0] . "' " .
                                                       "WHERE Field_3 = '" . $RETURNED_DATA_ARRAY[2] . "'");
            eval {
                $UPDATE_TABLE->execute() or die "Database issue. $DBI::errstr\n";
            };

            if ($@) {
                print "ERROR: Cannot update table data.  The error was: $@";
            exit(2);
        }
    }
}