my $file_name="/source_file/source_file.txt";
print LOG "Opening the file \n";
open(SRC_FILE,">$file_name")|| die "Can't open $file_name\n";
print SRC_FILE "USER_ID,USER_NAME,PRIMARY_GROUP,EMAIL \n";

$sql = "SELECT user_id,user_name,primary_group,email from users";

my $sth=$db->prepare($sql);
$sth->execute
|| die "Can't execute the query\n";

while (@row =$sth->fetchrow_array)
{
print SRC_FILE "$$row[0][0]" \n";
}

##</code><code>##

USER_ID	USER_NAME PRIMARY_GROUP	 EMAIL 
abcd 	arun	  app_dev	 arun@abc.com
pvad	rani	  consultant	 rani@abc.com