html form with white fields to mysql - php

Question

I don't understand what is the correct way to pass the html form fields to mysql database in case one of the fields is empty.
I have this html:
<form name="formName" method="POST" action="" onsubmit="registra();">
<label for="datetime1">datetime one</label>
<input type="datetime-local" id="datetime1" name="datetime1">
<label for="datetime2">datetime two</label>
<input type="datetime-local" id="datetime2" name="datetime2">
<button type="submit">Salva</button>
</form>
<script>
function registra() {
var datetime1 = document.forms['formName']['datetime1'].value;
datetime1 = new Date(datetime1).toISOString().slice(0, 19).replace('T', ' ');
var datetime2 = document.forms['formName']['datetime2'].value;
datetime2 = new Date(datetime1).toISOString().slice(0, 19).replace('T', ' ');
jQuery.ajax({
type: "POST",
url: "./functions.php",
data: {
action: 'registraForm',
id: <?php echo $id; ?>,
datetime1: datetime1,
datetime2: datetime2
}
}).done(function( response ) {
alert( response );
});
}
</script>
And this php:
<?php
/* AJAX */
if(isset($_POST['action']) && !empty($_POST['action'])) {
$action = $_POST['action'];
switch($action) {
case 'registraForm' : registra_form();break;
}
}
function registra_form() {
$dbhost = "localhost";
$dbuser = "user";
$dbpass = "pass";
$db = "db";
$conn = new mysqli($dbhost, $dbuser, $dbpass,$db) or die("Connect failed: %s\n". $conn -> error);
$id = $_POST['id'];
$datetime1 = ($_POST['datetime1']?$_POST['datetime1']:NULL);
$datetime2 = ($_POST['datetime2']?$_POST['datetime2']:NULL);
if ( /* update mysql row */ ) {
$sql = "UPDATE table SET datetime1='$datetime1', datetime2 = '$datetime2', WHERE id=$id";
} else {
$sql = "INSERT INTO table (id, datetime1, datetime2) VALUES ($id, '$datetime1', '$datetime2')";
}
if ($conn->query($sql) === TRUE) {
echo 'done!';
} else {
echo "Error: " . $sql . "<br>" . $conn->error;
}
die();
$conn -> close();
}
In the database both datetime1 and datetime2 are set as timestamp type with default null.
If both datetime1 and datetime2 are filled, the registration is successful. If instead one of the two fields of the form is not filled I receive a sql syntax error.
Something like error: UPDATE table SET datetime1='2020-04-17 11:06:00', datetime2='' WHERE id=5 Incorrect datetime value:'' for column db.table.datetime2 at row 2
I think this is the problem $datetime2 = ($_POST['datetime2']?$_POST['datetime2']:NULL); but I don't know how to solve it.
Thanks
Fosco

Answer 1

Ok this is "an answer" and not a pretty one, based upon your supplied code/issue.
Personally I would not code it this way, but we cannot give tutorials on here.
This is more a demonstration on how to go about working something out, without all the in between bits.
This is an example. Test Code (something we should learn to write), I used to test getting the correct SQL Statements.
function test_datetime_sql()
{
$_POST['datetime1'] = '';
$_POST['datetime2'] = '2020-04-17 11:06:00';
// There must be a more elegant way to do this
$datetime1 = $_POST['datetime1']?"'".$_POST['datetime1']."'":'NULL';
$datetime2 = $_POST['datetime2']?"'".$_POST['datetime2']."'":'NULL';
echo '<pre>';
echo 'LINE: '. __LINE__. ' Module '.__CLASS__.'<br>';
var_dump($datetime1);
echo '</pre>';
echo '<pre>';
echo 'LINE: '. __LINE__. ' Module '.__CLASS__.'<br>';
var_dump($datetime2);
echo '</pre>';
$id = 5;
$sql = "UPDATE table SET
datetime1 = $datetime1,
datetime2 = $datetime2,
WHERE id=$id";
var_dump($sql); // What SQL do we get
}
Give that a try by generating the SQL and testing it.
Notice that its a change to the Ternary AND the SQL statement - notice the lack of '' in the $sql for datetime1 and datetime2 as they are generated in the ternary.
What is happening here is if it is a "Not Empty" Value, it's getting wrapped in '' to make it a string.
The same occurs with NULL
I strongly suggest you copy and paste this somewhere and play with it to see what happens.
In your original code, when you set $datetime1 as NULL it appears in your SQL as $datetime1 = '' and NOT as $datetime1 = NULL ( Not the string 'NULL' ).