mysql命令由rand PHP

Question

I am using

$nameimg = mysql_query("SELECT * 
                        FROM images 
                        WHERE id='".$row['imgID']."' 
                        ORDER BY RAND()    
                        LIMIT 10");

To show random images by said user, but it's not showing random images. It's just showing via time submitted.

Answer 1

WHERE conditions checking for an ID usually reduce the result set to one row, so the whole ORDER BY clause becomes useless.

You should think about your schema and redesign the query.

Answer 2

You should rather use PHP to randomly shuffle the array. If the field you are interested in is called url :

$req = mysql_query("SELECT url FROM images WHERE user_id = '{$row['userID']}'");
$images = array();
while($image = mysql_fetch_array($req)) {
    $images[] = $image['url'];
}
shuffle($images);
$tenImages = array_slice($images, 0, 10);

Edit. And please consider using PDO for prepared statements .

Update. Why not picking the ten images one at a time?

$images = array();
while(count($images) < 10) {
    $req = mysql_query("SELECT url FROM images WHERE user_id = '{$row['userID']}' LIMIT " . rand(1, 10000) . ", 1");
    $image = mysql_result($req, 0, 0);
    if(!in_array($image)) {
        $images[] = $image;
    }
}

Funnier (and faster) way. Provided here .

$ids = array();
for($i = 0 ; $i < 1000 ; $i++) {
    $ids[] = rand(1, 10000);
}
$req = mysql_query("SELECT url FROM images WHERE user_id = '{$row['userID']}' AND id IN (" . implode(',', $ids) . ") LIMIT 10");