MySQL SELECT COUNT返回NULL

Question

I'm trying to get the number of comments on a particular item.

$stmt1 = $conn->prepare("SELECT COUNT(r_value) FROM ratings WHERE r_snippet=? AND r_value=3 OR r_value=2");
$stmt2 = $conn->prepare("SELECT COUNT(c_id) FROM comments WHERE c_snippet=?");

foreach ($snippets as $snippet){

    $s_id = $snippet['s_id'];
    $s_thumb = $snippet['s_thumb'];

    $stmt1->bind_param("i",$s_id);
    $stmt1->execute();
    $stmt1->bind_result($numLikes);
    $stmt1->fetch();

    $stmt2->bind_param("i",$s_id);
    $stmt2->execute();
    $stmt2->bind_result($numComments);
    $stmt2->fetch();

?>

    ** HTML here **    

<?php 

}

$stmt1->close();
$stmt2->close();

?>

$numLikes works fine, but $numComments seems to be returning NULL (from var_dump ) and I'm not sure why. The SQL in phpMyAdmin works fine and returns the number of comments...

Answer 1

You probably want change this for your first query

... AND r_value=3 OR r_value=2

To

... AND (r_value=3 OR r_value=2)

OR THIS

... AND r_value IN (2,3)

---

But for the second query try something simple just for debug

$stmt2 = $conn->prepare("SELECT * FROM comments WHERE c_snippet=10");

then

$stmt2 = $conn->prepare("SELECT count(*) FROM comments WHERE c_snippet=10");