php - MySQL RAND() 不工作，总是得到相同的结果

Question

我有这个 MySQL 查询:

while ($x <= 9) {
   $data_1 = "SELECT scene FROM star WHERE star LIKE '%".$star."%' ORDER BY RAND() LIMIT  1";
   $result_1 = mysql_query ($data_1) OR die("Error: $data_1 </br>".mysql_error());

   while($row_1 = mysql_fetch_object($result_1)) {
      $scene = $row_1->scene;
      $x = $x + 1;
   }
} 

我想每次执行时都获得一个新场景，但我总是得到相同的场景。有什么问题吗？有人可以给我一些指示，我必须朝哪个方向搜索吗？

Answer 1

您需要做的是将随机种子绑定(bind)到每一行，并每次绑定(bind)一个新种子。为此，请向表分配一个随机值作为别名 transient 列，然后从中进行选择。

SELECT s.scene as scene FROM (
    SELECT stars.scene as scene, RAND() as seed 
      FROM stars
     WHERE star LIKE '%".$star."%' 
  ORDER BY seed
) s
LIMIT  1;

使用PDO它看起来像这样:

function getScene() {
    $sql = 'SELECT s.scene as scene FROM ( SELECT stars.scene as scene, RAND() as seed FROM stars WHERE star LIKE '%:star%' ORDER BY seed ) s LIMIT  1;';
    $query = $this->db->prepare($sql);//'db' is the PDO connection
    $query->execute(array(':star' => "Allison Brie"));

    foreach ($conn->query($sql) as $row) {
        print $row['scene'] . "\t";
    }
}

我不确定你想用其余的代码来完成什么，但它看起来大多很糟糕。