update only not null input value in mysql using PHP - php

Question

i have a database contain thousands of row, the user can update his/her row by providing the updated values, i need to update the row only with a non null values provided by the user, if the value provided by user is null the previous data should be remain, for example:
id=1
name = John
address = USA
if the user provide name with null value and address with UK value then the data should be:
id=1
name =John
address = UK
any help with php code example will be highly appreciated.

Answer 1

You should loop through the $_POST superglobal and construct a new array for insertion that does not include the nulls, then use that for your query instead of $_POST directly.
$update = array();
foreach ($_POST as $key => $value) {
if(!is_null($value) && !($value == ''))
$update[$key] = $value;
}
Then use $update for your query parameters, which should not contain any null or blank values.

Answer 2

I use PDO connection
First create a table and insert as follows
create table testing(id int(11), name varchar(100),address varchar(200));
insert into testing values(100,'Null','California');
insert into testing values(200,'sectona','California');
pdo_connect.php
<?php
$db = new PDO (
'mysql:host=localhost;dbname=yourdbname;charset=utf8',
'root', // username
'root' // password
);
?>
<?php
pdo_connect.php
// from form inputs
/*
$id=$_POST["id"];
$name=$_POST["name"];
$address=$_POST["address"];
*/
// direct variable initialisation
/*
$id='100';
$name = 'John';
$name = 'Null';
$address = 'California';
*/
// initialize a null value
$check ='Null';
// check null value for name variable in the first insert statement
$resultn = $db->prepare('SELECT * FROM testing where name = :name');
$resultn->execute(array(
':name' => 'Null'
));
while ($row = $resultn->fetch())
{
$nm = $row['name'];
}
if ($nm == $check)
{
echo '<b><font color=red><b></b>You cannot update with a Null Value</font></b>';
exit();
}
// update if name is not null
$update = $db->prepare('
UPDATE testing SET
name = :name,address = :address
WHERE id= :id');
$update->execute(array(
':name' => 'yourname',
':address' => 'USA',
':id' => '100'
));
echo 'update successful';
?>
finall to update using a non null value from database, then substitute the code below in the query statements
$resultn = $db->prepare('SELECT * FROM testing where name = :name');
$resultn->execute(array(
':name' => 'sectona'
));