如何管理空IN sql查询？

Question

$ids = array(1,2,3);
$in = implode(',',$ids);

$query = "SELECT * FROM user where user_id IN ($in) ";

查询没有问题.但是什么时候$ids是空阵$ids = array();

我正确地得到了sql查询错误,因为SELECT * FROM user where user_id IN ()它不是一个有效的查询.

如何在不检查空数组的情况下避免这种情况,即无论如何都要进行查询运行？

Answer 1

$ in为空时,不应运行查询.我认为你需要的是这样的

$in = implode(',',$ids);
if($in) {
     $query = "SELECT * FROM user where user_id IN ($in) ";
 }
 else {
      //alternate scenario here
 }

编辑

$in = implode("','",$ids); // generate like 1','2
$query = "SELECT * FROM user where user_id IN ('$in') "; //  if has  1','2 surrond it with quote make it IN('1','2') and if empty than IN('')

Answer 2

管理这个的最佳方法是:

$in = implode("','",$ids); // generate like 1','2
$query = "SELECT * FROM user where user_id IN ('$in') "; //  if has  1','2 surrond it with quote make it IN('1','2') and if empty than IN('')

这样可以省去if/else结构和其他所有内容

Answer 3

你可以在$ ids字符串之前加0.毕竟No ID将从任何数据库中的0开始.

或者你可以这样做..

$sql = "SELECT * FROM user where ".($ids != ''? "user_id IN ($ids)" : " 1=1");