mysql updating data only where post contains data - php

Question

i have a simple form in html where user selects and ID from the table on the website (required data) and then he can / or not change 2 fields. First is a dropdown list of 2 values (strings), and the second is number of open spots!
So if a user leaves both fields empty and click send by mistake nothing should happen. If a user only changes one of the fields only that one should change!
I have checked every forum and almost all posts in here and i still cannot get it to work.
<form action="viv_settings_tecaji.php" method="post">
Datum termina (izberi ID):
<input type="number" name="ID" required><br><br>
<!--Sprememba tega datuma (če ne želiš spremenit pusti prazno):
<input type="date" name="nov_datum"><br><br>-->
Sprememba statusa (če želiš da ostane isto vpiši trenutni status!:
<select name="STATUS">
<option></option>
<option value="zaprt">Zaprt</option>
<option value="odprt">Odprt</option>
</select><br><br>
Sprememba števila odprtih mest
<input type="number" name="st_odprtih_mest"><br><br>
<input type="submit">
</form><br>
php
<?php
$servername = "localhost";
$username = "root";
$password = "";
$dbname = "viverius_education";
$conn = new mysqli($servername, $username, $password, $dbname);
if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
}
echo "Connected successfully";
$update_status = $_POST['STATUS'];
$update_st_odprtih_mest = $_POST['st_odprtih_mest'];
$update_ID = $_POST['ID'];
if (empty($update_status) AND empty($update_status)){
header('Location: viv_settings_tecaji_main.php'); exit;
}
else{
$sql = "UPDATE razpisani_tecaji
SET
STATUS = IF('$update_status'='',STATUS,'$update_status'),
ST_ODPRTIH_MEST = IF('$update_st_odprtih_mest'='',STATUS,'$update_st_odprtih_mest'),
WHERE ID_TECAJA = $update_ID";
}
if ($conn->query($sql) === TRUE) {
echo "New record created successfully";
header('Location: viv_settings_tecaji_main.php'); exit;
} else {
echo "Error: " . $sql . "<br>" . $conn->error;
}$conn->close();
?>

Answer 1

A decent form example would be like the following
<form action='' method='post'>
<input type='text' name='field1' required>
<select name='fieldSelect'>
<option value='value1'>Value1</option>
<option value='value2'>Value2</option>
</select>
<input type='submit' name='send'>
</form>
then the PHP would be like
<?php
if(isset($_POST['send'] && (!empty($_POST['field1']) || !empty($_POST['fieldSelect']))){
$field1 = $_POST['field1'];
$fieldSelect = $_POST['fieldSelect'];
//YOUR SQL CODE
} else {
echo "Please Insert Some Data";
}
?>
In brief:
Give your Submit button a name
Check if the submit button is clicked or not by if(isset($_POST['submit-button-name'])){}
define your form's $_POST variables with names.
Continue with SQL.

Answer 2

There are a couple of ways you can avoid inserting "empty" records in your database. It depends if you want to do it in the client-side (before the form submits) or server-side (when the form is submitted to the server).
I'll show you how to do it server-side, since you posted your php script.
In viv_settings_tecaji.php
...
$update_status = $_POST['STATUS'];
$update_st_odprtih_mest = $_POST['st_odprtih_mest'];
$update_ID = $_POST['ID'];
if($update_status == "" || $update_st_odprtih_mest == "" || $update_ID == ""){
die("One of the form fields was empty");
}
...
That would kill your script if any of the form fields was empty. Potentially, you could check for null or use PHP's empty() function.
I hope this helps!

Answer 3

So i manege to get it to work using the following code. So for the part if user leaves both field empty i will put together a script for at least 1 to be required.
$sql = "UPDATE razpisani_tecaji
SET
STATUS = IF(LENGTH('$update_status')=0, STATUS, '$update_status'),
ST_ODPRTIH_MEST = IF(LENGTH('$update_st_odprtih_mest')=0, ST_ODPRTIH_MEST, '$update_st_odprtih_mest')
WHERE ID_TECAJA = $update_ID";