PHP variables within SQL Query not being interpreted properly

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I am having difficuly understanding why this code is not working properly. I have tried using similar code without variables and it works just fine. I am guessing its my use of variables inside of the SQL Query which is messing up the interpretation. any help would be appreciated!\[code\]$connect = mysqli_connect("localhost", "root", "root");mysqli_select_db($connect, "db_name");$trigger = (is_numeric($_POST['trigger']) ? (int)$_POST['trigger'] : 0);if($trigger) { $fetch = mysqli_query($connect, "SELECT * FROM Switches WHERE PinNumber ={$trigger} "); $row = mysqli_fetch_array($fetch); if($row['SwitchStatus'] == 0) { $changeValue = http://stackoverflow.com/questions/15869607/mysqli_query($connect,"UPDATE Switches SET SwitchStatus=1 WHERE PinNumer={$trigger} " );} else if($row['SwitchStatus'] == 1) { $changeValue = http://stackoverflow.com/questions/15869607/mysqli_query($connect,"UPDATE Switches SET SwitchStatus=0 WHERE PinNumer={$trigger} " );} else { echo("Error switchTrigger, con2, temp.php") ;}}$fetchStatus = mysqli_query($connect, "SELECT * FROM Switches WHERE PinNumber ={$trigger} ");$statusCheck = mysqli_fetch_array($fetchStatus);echo( $trigger );mysqli_close($connect); \[/code\]