How to conditionally send email alert in perl - sql

Question

I have a perl script which is printing the table content from Oracle DB in HTML format.
My script will run on a daily basis , which will just email the o/p of the simple sql query (select query)
Now i want my script to stop email alert whenever record count of the table is NULL i.e no records in the table.
Here is my partial script
$retCode = executeSQL("select firstname,lastname,employee_id from employee");
if ($retCode) {
push(#HTML, "<tr><td> </td><td></td><td>");
push(#HTML, "<td></td><td></td></tr>\12");
}
push(#HTML, "</table>\12\12");
push(#HTML, "COUNT : $count\12");
&sendMail;
sub sendMail {
$sub = "sample data";
$from = 'xyz#abc.com';
$to = 'xys#abc.com';
open(MAIL, "|/usr/lib/sendmail -t");
print MAIL "From: $from \12"; print MAIL "To: $to \12";print MAIL "Cc: $Cc \12";
print MAIL "Subject: $sub \12";
print MAIL "Content-Type: text/html \12";
print MAIL "Content-Disposition:inline \12";
print MAIL #HTML;
close(MAIL);
}
sub executeSQL {
my $SQL = $_[0];
chomp($SQL);
print "$SQL\12";
my $hostname = $ENV{"ORACLE_DB"};
my $dbh = CommonFunctions::connect_DBI( $hostname, "USERNAME", "PASSWORD" )|| die "ERROR : Unable to connect to $hostname: $DBI::errstr\n\n";
my $sth = $dbh->prepare($SQL);
$sth->execute or die "EXEC ERROR $sth->errstr";
$count = 0;
while (#ary = $sth->fetchrow_array) {
$count++;
push(#HTML, "<tr>");
foreach(#ary) {
chomp($_);
push(#HTML, "<td>$_</td>");
print "$_,";
}
push(#HTML, "</tr>\12");
}
}

Answer 1

The solution is already there in the code. The program doesn't add table rows to the HTML body of the email if there are no rows returned from the DB query. Hence, you neeed to move the send command into that condition.
if($retCode) {
push(#HTML,"<tr><td> </td><td></td><td>");
push(#HTML,"<td></td><td></td></tr>\12");
push(#HTML,"</table>\12\12");
push(#HTML, "COUNT : $count\12");
&sendMail;
}

Answer 2

I think the big miss here is at the end of executeSQL where you failed to have a return clause indicating whether or not you found any rows in the query.
if (executeSQL("select firstname,lastname,employee_id from employee"))
{
push(#HTML, "<tr><td> </td><td></td><td>");
push(#HTML, "<td></td><td></td></tr>\12");
push(#HTML, "</table>\12\12");
push(#HTML, "COUNT : $count\12");
&sendMail;
}
sub sendMail {
# no changes
}
sub executeSQL {
my $SQL = shift;
print "$SQL\12";
my $hostname = $ENV{"ORACLE_DB"};
my $dbh = CommonFunctions::connect_DBI( $hostname, "USERNAME", "PASSWORD" ) ||
die "ERROR : Unable to connect to $hostname: $DBI::errstr\n\n";
my $sth = $dbh->prepare($SQL);
$sth->execute or die "EXEC ERROR $sth->errstr";
my $count = 0;
while (#ary = $sth->fetchrow_array) {
# no changes
}
$sth->finish;
$dbh->disconnect;
return $count; # this is what I think you're missing
}
That said, there is some other room for improvement, some of which has already been mentioned:
Consider passing a reference to #HTML instead of using it as a global -- loose coupling
Probably should close out your SQL -- I added the $sth->finish and $dbh->disconnect as examples
Have you looked into HTML::Table? I use it a lot, and it's a real time-saver. Creating HTML on the fly is always a last resort for me