MySql query not working with variables weird bug

Question

I have a list of users ids and my goal is to get the name of each user using the id

the sql variable prints: SELECT name FROM users WHERE unique_id = '56d4814fb37cf3.17691034 '

If i copy paste the query the name is returned and works as well with other ids, but i don't want the function to allways return the same name, i want to add the variable $userID to my query and return the name

But this only works when i hardcode de id

public function returnNameByID($userID){
 //User ID: 56d4814fb37cf3.17691034 
	
    $sql =  "SELECT name FROM users WHERE unique_id = '$userID'";
	
  echo $sql; // Prints SELECT name FROM users WHERE unique_id = '56d4814fb37cf3.17691034 '
	
//Doesn't work $name returns Null
//  $stmt = $this->conn->prepare("SELECT name FROM users WHERE unique_id = '$userID'"); 

//Doesn't work $name returns Null
	$stmt = $this->conn->prepare($sql); 

// Works $name returns name of the user
   $stmt = $this->conn->prepare(" SELECT name FROM users WHERE unique_id = '56d4814fb37cf3.17691034 ' "); 

    $stmt->execute();
	
    $result = $stmt->get_result()->fetch_assoc();
	
    $name = $result["name"];

    return $name;

EDIT

require_once 'db_functons.php';
$db = new db_functions();

$userID = $_GET['userID'];
$mArray =  array();

$mArray = $db->getFriendsList($userID);
//Printing the array Prints the correct id's

$name = $db->returnNameByID($mArray[0]);
echo $name;

I removed the extraneous database tags. Feel free to add the tag for the database you are really using. — Gordon Linoff
– Gordon Linoff, Commented Mar 13, 2016 at 19:02
'56d4814fb37cf3.17691034 ' see that trailing space? Remove it. — Funk Forty Niner
– Funk Forty Niner, Commented Mar 13, 2016 at 19:02
this line works: $stmt = $this->conn->prepare(" SELECT name FROM users WHERE unique_id = '56d4814fb37cf3.17691034 ' "); removing the space makes no diference, but this // $stmt = $this->conn->prepare("SELECT name FROM users WHERE unique_id = '$userID'"); and this $stmt = $this->conn->prepare($sql); don't — Tiago Oliveira
– Tiago Oliveira, Commented Mar 13, 2016 at 19:07
The problem is that the $userID in the function has some random blank characters on the end of it. On the first line of your function $userID = trim($userID); — Matt
– Matt, Commented Mar 13, 2016 at 19:27

ScaisEdge · Accepted Answer · 2016-03-13 19:29:50Z

2

Seems you have some space around your code try using a trim

$sql =  "SELECT name FROM users WHERE trim(unique_id) = '" . trim($userID) . "';";

answered Mar 13, 2016 at 19:29

ScaisEdge

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2 Comments

Matt Over a year ago

Yay, someone gets it. One thing that I would suggest is just adding that you should probably bind the parameter $userID rather than inserting it directly into the query (just good practice)

ScaisEdge Over a year ago

Yes in some case the string construction is not clear and in the way i proposed the evaluation of the var content is explicitally clear ..

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