call to function query on non object - php

Question

This function returns only one row from database while there are many of them.
Could someone tell me why please? Can i do this other way?
function writecomments($photoid){
include 'connect.php';
$stmt = $pdo -> query("SELECT * FROM comments WHERE photoid = '".$photoid."' ");
while($row = $stmt -> fetch()) {
return $row['comment'];
}
$stmt->closeCursor();
}
I have also tried this way:
function writecomments($photoid){
include 'connect.php';
$stmt = $pdo -> query("SELECT * FROM comments WHERE photoid = '".$photoid."' ");
while($row = $stmt -> fetch()) {
$allcomments = $allcomments . " " . $row['comment'];
}
return $allcomments;
$stmt->closeCursor();
}

Answer 1

Im assuming $pdo is a PDO connection object. In which case it could be to do with the fact you are using PDO::query - which is a bit of a tricky function - and how you are iterating through the result set.
If you want to use the PDO query method then it should be within a foreach loop.
From the PDO query official documentation
PDO::query() executes an SQL statement in a single function call, returning the result set (if any) returned by the statement as a PDOStatement object.
If you do not fetch all of the data in a result set before issuing
your next call to PDO::query(), your call may fail.
I would try:
function writecomments($photoid){
include 'connect.php';
foreach ($pdo -> query("SELECT * FROM comments WHERE photoid = '".$photoid."' ") as $row) {
return $row['comment'];
}
$stmt->closeCursor();
}

Answer 2

That's what fetch() does it returns the next row from the result
set. If you need all rows you will need to manually append them to an array, or use fetchAll() instead in order to get all rows at once.
It looks a little weird to have an include inside of the function, should be passed as parameter or maybe create the connection in the function.
Use prepared statements for this query.
I would do it this way:
Function:
function writecomments($pdo, $photoid){
$sql = "
SELECT *
FROM comments
WHERE photoid = ?
";
$stmt = $pdo -> prepare($sql);
$stmt->execute(array($photoid));
$rows = $stmt->fetchAll();
//return all rows
return $rows;
}
Usage:
include 'connect.php';
$rows = writecomments($pdo, $photoid);
var_dump($rows);