How to check if database values are null?

Question

I'm new to PHP/SQL and very confused.

In my SQL database, I have the following values for a user:

In my PHP script, echoing these values gives me 0.

Query:

$query = "SELECT * FROM user WHERE email = '{$email}'";
$result = mysqli_query($con, $query);
$row = mysqli_fetch_array($result);

I specify the email linked to the above user in the database. I get the desired row as a result (user ID 13 and these null values). Still, the code gets inside this if statement:

if (!empty($row['first_name']) && !empty($row['last_name']) && 
!empty($row['age']) && !empty($row['picture_path'])) {
    echo "inside";
}

Echoing the values themselves gave me 0 instead of null. Why? And how can I properly check for empty/null?

Thanks loads.

if you want to check in php, you can use [is_null()](http://php.net/manual/en/function.is-null.php), otherwise you want to use mysql you can use [ifnull, COALESCE](http://stackoverflow.com/questions/18528468/what-is-the-difference-bewteen-ifnull-and-coalesce-in-mysql) — Emilio Gort, Mar 06 '15 at 04:05
I think there's a misunderstanding. I am correctly retrieving this exact row inside my database. The problem lies when I evaluate the values and get 0 instead of null. I just edited my question to eliminate any confusion. — LPB, Mar 06 '15 at 04:25
`$var = is_null($row['name']) ? 'Null' : $row['name']; echo $var;` — Emilio Gort, Mar 06 '15 at 04:50

score 0 · Answer 1 · answered Mar 06 '15 at 03:52

0

You can just assign a certain string if a certain value is null using COALESCE() function. See below:

"SELECT 
       COALESCE(user_id,'null')user_id,
       COALESCE(first_name,'null')first_name,
       COALESCE(middle_name,'null')middle_name,
       COALESCE(last_name,'null')last_name,
       COALESCE(rs_status,'null')rs_status,
       COALESCE(age,'null')age,
       COALESCE(town,'null')town,
       COALESCE(phone,'null')phone,
       COALESCE(picture_path,'null')picture_path
 FROM user 
WHERE email = '{$email}'"

answered Mar 06 '15 at 03:52

Rigel1121

2,022
1
17
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I see, so I would test against that assigned string. It's clever, but isn't there a simpler way? – LPB Mar 06 '15 at 04:05
That's the simpler way that I know. – Rigel1121 Mar 06 '15 at 05:00

score 0 · Answer 2 · answered Mar 06 '15 at 04:56

0

PHP empty('0') returns true; to test for null use is_null($var).

Not intuitive but that's what it is.

answered Mar 06 '15 at 04:56

vladsch

606
6
7

How to check if database values are null?

2 Answers2