Simple html form using php and mysql. How do l maintain NULL values for empty fields in the database

Question

I have built a simple html form that has input boxs and text areas, which are then inserted into a mysql database with the help of php script. Not all the fields have to be filling in and l want to be able to search the database for NULL fields. My problem is that when the form submits, even entries that have no information are having something inserted like an empty space which means l then can't search the DB for NULL fields as returns everything.

This is the php script that sends the MYSQL insert query to the DB

<?php
/*Av Tech Name*/
$techNam = $_POST['techNam'];
/* Building */
$building = $_POST['building'];
/* Room */ 
$roomNum = $_POST['roomNum'];
/* Day */
$day = $_POST['day'];
/*Month*/
$month = $_POST['month'];
/*Projector Power */
$projPower = $_POST['projPower'];
/* Screen decends and retracts */
$screenUpDown = $_POST['screenUpDown'];
/* Power to buton control */
$controlPower = $_POST['controlPower'];
/* Lamp working */
$projLamp = $_POST['projLamp'];
/* Rips and tears to the screen */
$rips = $_POST['rips'];
/* Control Functions */
$controlFunctions = $_POST['controlFunctions'];
/* Projector image */
$projImage = $_POST['projImage'];
/* Screen Notes */
$screenNotes = $_POST['screenNotes'];
/* Control Notes */
$controlNotes = $_POST['controlNotes'];
/* Monitor power */
$monitorPower = $_POST['monitorPower'];
/* Network connection */
$networkConnect = $_POST['networkConnect'];
/* PC Power */
$pcPower = $_POST['pcPower'];
/* PC image */
$pcImage = $_POST['pcImage'];
/* PC audio */
$pcAudio = $_POST['pcAudio'];
/* PC DVD playback */
$pcDvd = $_POST['pcDvd'];
/* BluRay Player power */
$BluRayPower = $_POST['BluRayPower'];
/* Laptop VGA connection */
$laptopVga = $_POST['laptopVga'];
/* Visualiser Power */
$visPower = $_POST['visPower'];
/* bluRay Play back */
$BluRayPlay = $_POST['BluRayPlay'];
/* Laptop audio */
$laptopAudio = $_POST['laptopAudio'];
/* Visualiaser lamp */
$visLamp = $_POST['visLamp'];
/* BluRay Audio */
$BluRayAudio = $_POST['BluRayAudio'];
/* laptop HDMI */
$laptopHdmi = $_POST['laptopHdmi'];
/* Visualiser image */
$visImage = $_POST['visImage'];
/* Laptop Network Connection */
$laptopNetwork = $_POST['laptopNetwork'];
/* Visualiser automatic and manual zoom */
$visZoom = $_POST['visZoom'];
/* Lectern mic working */
$micLec = $_POST['micLec'];
/* Video conference power */
$vcPower = $_POST['vcPower'];
/* Condition of lectern Condition */
$lecternCondition = $_POST['lecternCondition'];
/* Radio mics working */
$audioRadioMics = $_POST['audioRadioMics'];
/* VC unit dials and connects */
$vcConnect = $_POST['vcConnect'];
/* General condition of cables Good */
$cableCondition = $_POST['cableCondition'];
/* Visualiser audio */
$vcAudio = $_POST['vcAudio'];
/* Condition of wall connections */
$wall = $_POST['wall'];
/* Visualiser laptop connection */
$vcLaptop = $_POST['vcLaptop'];
/* White board condition */
$whiteB = $_POST['whiteB'];
/* Video conference notes */
$vcNotes = $_POST['vcNotes'];

$sql = "INSERT INTO avChecklist (techNam, building, roomNum, day, month, 
projPower, screenUpDown, controlPower, projLamp, rips, controlFunctions, 
projImage, screenNotes, controlNotes, monitorPower, networkConnect, 
pcPower, pcImage, pcAudio, pcDvd, BluRayPower, laptopVga, visPower, 
BluRayPlay, laptopAudio, visLamp, BluRayAudio, laptopHdmi, visImage, 
laptopNetwork, visZoom, micLec, vcPower, lecternCondition, 
audioRadioMics, vcConnect, cableCondition, vcAudio, wall, vcLaptop, 
whiteB, vcNotes) VALUES ('$techNam', '$building', '$roomNum', '$day', 
'$month', '$projPower', '$screenUpDown', '$controlPower', '$projLamp', 
'$rips', '$controlFunctions', '$projImage', '$screenNotes', 
'$controlNotes', '$monitorPower', '$networkConnect', '$pcPower', 
'$pcImage', '$pcAudio', '$pcDvd', '$BluRayPower', '$laptopVga', 
'$visPower', '$BluRayPlay', '$laptopAudio', '$visLamp', '$BluRayAudio', 
'$laptopHdmi', '$visImage', '$laptopNetwork', '$visZoom', '$micLec', 
'$vcPower', '$lecternCondition', '$audioRadioMics', '$vcConnect', 
'$cableCondition', '$vcAudio', '$wall', '$vcLaptop', '$whiteB', 
'$vcNotes')";

 if (!mysql_query($sql)) {
 die('Error: ' . mysql_error());
 }
echo 'Thanks '. $techNam .' your completed maintenance check for room '. 
$roomNum .'  has been added to the database.';
echo "<br /><br /><br />";
echo 'This page will redirect in 5 seconds';
mysql_close();
?>

Table Structure

Database a9404870_heAv
Table structure for table avChecklist
Field   Type    Null    Default
submitDate  timestamp   Yes CURRENT_TIMESTAMP
techNam varchar(255)    Yes NULL
building    varchar(255)    Yes NULL
roomNum varchar(255)    Yes NULL
day varchar(255)    Yes NULL
month   varchar(255)    Yes NULL
projPower   varchar(255)    Yes NULL
screenUpDown    varchar(255)    Yes NULL
controlPower    varchar(255)    Yes NULL
projLamp    varchar(255)    Yes NULL
rips    varchar(255)    Yes NULL
controlFunctions    varchar(255)    Yes NULL
projImage   varchar(255)    Yes NULL
screenNotes varchar(255)    Yes NULL
controlNotes    varchar(255)    Yes NULL
monitorPower    varchar(255)    Yes NULL
networkConnect  varchar(255)    Yes NULL
pcPower varchar(255)    Yes NULL
pcImage varchar(255)    Yes NULL
pcAudio varchar(255)    Yes NULL
pcDvd   varchar(255)    Yes NULL
BluRayPower varchar(255)    Yes NULL
laptopVga   varchar(255)    Yes NULL
visPower    varchar(255)    Yes NULL
BluRayPlay  varchar(255)    Yes NULL
laptopAudio varchar(255)    Yes NULL
visLamp varchar(255)    Yes NULL
BluRayAudio varchar(255)    Yes NULL
laptopHdmi  varchar(255)    Yes NULL
visImage    varchar(255)    Yes NULL
laptopNetwork   varchar(255)    Yes NULL
visZoom varchar(255)    Yes NULL
micLec  varchar(255)    Yes NULL
vcPower varchar(255)    Yes NULL
lecternCondition    varchar(255)    Yes NULL
audioRadioMics  varchar(255)    Yes NULL
vcConnect   varchar(255)    Yes NULL
cableCondition  varchar(255)    Yes NULL
vcAudio varchar(255)    Yes NULL
wall    varchar(255)    Yes NULL
vcLaptop    varchar(255)    Yes NULL
whiteB  varchar(255)    Yes NULL
vcNotes varchar(255)    Yes NULL

Answer 1

In order to make sure something is set to NULL you have to do something like this:

isset($_POST['screenNotes'])? $screenNotes = $_POST['screenNotes'] : $screenNotes = NULL;

You have to do this for every field that you wish to insert NULL's if the field is left blank.

What I have done here is use a ternary condition - it is just a shortened if condition:

<if this is true> ? <do this> : <else do that>;

For more on ternary operatores see the docs .