php query not working, no error in sql

Does your query work when run in phpMyAdmin?

Then look at the contents of your variables $dayBeforeNew and $dayAfterNew

What data type is 4g_statistic.Day ? Is it date(time)? Yes, then you are missing single quotes.

afaik, in phpmyadmin queries are pasted in raw text, in php you're putting the query inside of double quotes " //query here ". But that does not mean that the variable embedded is considered string, unless you put single quotes ' //varname here '.

I just use curly brackets around the variables, and you don't need ` marks in the array reference later on. You also want to screen the GET input to make sure someone isn't going to drop your database. I also try not to use key words for table names, like reference. Maybe you need to say `reference` instead, but if it runs on the SQL server it will work in PHP.

 $dayBeforeNew = $_GET['daybefore']; $dayAfterNew = $_GET['dayafter']; if(!ctype_digit($dayBeforeNew)){$dayBeforeNew = 1;}//Prevent an SQL INJECTION NIGHTMARE if(!ctype_digit($dayAfterNew)){$dayAfterNew = 1;}//Prevent an SQL INJECTION NIGHTMARE $sql = "SELECT reference.LOCID, reference.Region, Sitename, (SELECT `Data Total Traffic` from 4g_statistic where reference.LOCID = 4g_statistic.LOCID AND 4g_statistic.Day = {$dayBeforeNew}) as `pre.Data Total Traffic`, (SELECT `L_25_VoLTE Traffic (Erlang)` from 4g_statistic where reference.LOCID = 4g_statistic.LOCID AND 4g_statistic.Day = {$dayAfterNew}) as `pre.L_25_VoLTE Traffic (Erlang)` FROM `reference`"; $res = mysqli_query($conn, $sql) or die(mysqli_error($conn)); while($row = mysqli_fetch_array($res)) { ?> <tr> <td><?php echo $i; $i++; ?></td> <td><?php echo $row['LOCID']; ?></td> <td><?php echo $row['Sitename']; ?></td> <td><?php echo $row['Region']; ?></td> <td><?php echo $row['pre.Data Total Traffic']; ?></td> <td><?php echo $row['pre.L_25_VoLTE Traffic (Erlang)']; ?></td> </tr> <?php }