Where和Order By子句不起作用

Question

所以这段代码不起作用，我无法弄清楚。

$productid = (isset($_REQUEST['productId'])) ? $_REQUEST['productId'] : ''; 

$query = "SELECT * FROM products WHERE productId = '$productid' ORDER BY rand() limit 3"; 

Answer 1

也许尝试：

$productid = (isset($_REQUEST['productId'])) ? $_REQUEST['productId'] : ''; 
if ($productid != ''){ 
    $query = "SELECT * FROM products WHERE productId = '$productid' ORDER BY rand() limit 3"; 
} else { 
    $query = "SELECT * FROM products ORDER BY rand() limit 3"; 
} 

这将返回所有的产品，如果产品ID没有过来。