How to omit NULL values when trying to UPDATE a table - php

Question

I am fetching values from a form something like this
$value = mysql_real_escape_string($_POST['id']);
$value1 = mysql_real_escape_string($_POST['name']);
$value2 = mysql_real_escape_string($_POST['age']);
And I am using a mysql syntax like this to store information in DB
$sql = "UPDATE table SET name='$value1',age='$value2' WHERE id ='$value'";
I want the above mentioned UPDATE syntax to work only if the values are not NULL or not left blank.
For example if the name form is left blank and some value has been given for age than only age should be updated and not name..
How can I do this?

Answer 1

if(isset($_POST['id']) && isset($_POST['name']) && isset($_POST['age']))
{
$value = mysql_real_escape_string($_POST['id']);
$value1 = mysql_real_escape_string($_POST['name']);
$value2 = mysql_real_escape_string($_POST['age']);
$sql=" UPDATE table SET name='$value1',age='$value2' WHERE id ='$value'";
}
See: isset()

Answer 2

At a very basic level, you could check for non-null values using isset.
For example:
if(isset($_POST['id']) && isset($_POST['name']) && isset($_POST['age'])) {
// Do the insert...
}
However, I suspect you'll probably want to carry out some proper validation to ensure that the age is valid, etc. (Perhaps via if(intval($value2) !== 0) if that makes sense.)
Also, I'd really recommend not allowing the user to arbitrarily update database records. (POSTs are very easy to spoof, and the user could simply change the form 'id' value.)

Answer 3

You can use empty() to check if the values are null or blank.
if ( !empty( $value) && !empty( $value1 ) && !empty( $value2 ) ) {
// Do query
}
You should also check $_POST elements using isset() to ensure the values exists before using them:
if ( isset( $_POST['id'] ) ) {
$value = mysql_real_escape_string($_POST['id']);
}

Answer 4

if ((isset($_POST['id']) && ($_POST['id'] !== '')) &&
(isset($_POST['name']) && ($_POST['name'] !== '')) &&
(isset($_POST['age']) && ($_POST['age'] !== ''))) {
... everything ok ... do data base stuff
} else {
die("Not correct");
}

Answer 5

Try this:
//$value1 = 'joey';
$value2 = 123;
$sql = "UPDATE table SET ";
$sql .= !empty($value1) ? " name='{$value1}'," : null;
$sql .= !empty($value2) ? " age='{$value2}'," : null;
$sql = substr($sql, 0, -1);
$sql .= " WHERE id ='{$value}'";
echo $sql;
It should only update the variable that is not empty. Also do the escaping like others mentioned above.