MySQL Query not selecting data based on WHERE value

Question

I'm trying to return all records from my database where the userID is equal to the logged in user.

I have the following only for some reason its not returning anything, can anybody see any obvious errors?

<?php 
$interestsquery  = "SELECT * 
                      FROM user_interests 
                     WHERE user_id = $usersClass->userID()";
$result = mysql_query($interestsquery);

while($row = mysql_fetch_array($result, MYSQL_ASSOC)) {
    echo "{$row['interest']}";
} 
?>

Obvious that your PHP is not catching MySQL errors so you could debug... — OMG Ponies
– OMG Ponies, Commented Jul 3, 2011 at 20:42

cwallenpoole · Accepted Answer · 2011-07-03 20:42:40Z

5

Unfortunately, you can't call functions and have them parsed that way. You'll either need to concatenate manually, or set a variable and parse that.

Try this:

"SELECT * FROM user_interests WHERE user_id = " . $usersClass->userID();

Or this:

$uid = $usersClass->userID();
"SELECT * FROM user_interests WHERE user_id = $uid";

answered Jul 3, 2011 at 20:42

cwallenpoole

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2 Comments

Rahly Over a year ago

or "SELECT * FROM user_interests WHERE user_id = {$usersClass->userID()}"; but still he should be using the quoting function

cwallenpoole Over a year ago

yea... I don't like calling functions inside strings (Yes, I know it's different, but... somehow...)

Bill Karwin · Accepted Answer · 2011-07-03 20:45:27Z

4

The method call is a complex enough expression that you should probably enclose it in expression interpolation delimiters:

$interestsquery  = "SELECT * FROM user_interests WHERE user_id = {$usersClass->userID()}"

But I also recommend abandoning the primitive PHP/mysql extension and moving to PDO, so you can use query parameters. Then you don't have to hassle with string interpolation at all, and you gain better habits for writing code that resists SQL injection vulnerabilities.

$interestsquery  = "SELECT * FROM user_interests WHERE user_id = ?"
$stmt = $pdo->prepare($interestsquery);
$result = $stmt->execute(array( $usersClass->userID() ));

answered Jul 3, 2011 at 20:45

Bill Karwin

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2 Comments

Liam Over a year ago

Thanks Bill, Im still learning PHP so im very new to a lot of the things Im seeing here, would it be wise to read up on PDO now or wait until I understand the entire fundamentals of PHP first?

Bill Karwin Over a year ago

PDO is really not that hard. I recommend using PDO and forgetting that the plain mysql extension exists. I wish that they'd deprecate the mysql extension.

Ovais Khatri · Accepted Answer · 2011-07-03 20:42:25Z

2

try this:

$interestsquery  = "SELECT * FROM user_interests WHERE user_id =".$usersClass->userID();

answered Jul 3, 2011 at 20:42

Ovais Khatri

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Comments

Emre Yazici · Accepted Answer · 2011-07-03 20:43:12Z

2

Try

$interestsquery  = "SELECT * FROM user_interests 
                    WHERE user_id = ".$usersClass->userID();

And make sure $usersClass->userID() returns a valid integer user id.

answered Jul 3, 2011 at 20:43

Emre Yazici

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