php - 将空值传递给mysql一样的查询

我的SQL是这样的：

$si_like_param="%".$si_gl_group_id."5";
$stmt = $db->prepare("select  m1.id, m1.name, m1.surname, m1.fathername,
                              m1.region_num,m1.school_num,m1.variant,
                              m1.sinif, m1.qrup,m1.f_lan
                      from  students_answers m1,
                            results m2
                      where
                            m1.id_exam=:si_exam_id
                        and m1.id=m2.st_answer_id
                        and m2.result_level >= :si_min_score
                        and m1.school_num in ('003','018','019','020')
                        and m1.region_num = 20
                        and m1.qrup like :si_group_id
                      order by m2.result_level desc;");

$stmt->bindparam(":si_exam_id", $si_exam_id);
$stmt->bindparam(":si_min_score", $si_min_score);
$stmt->bindparam(":si_group_id", $si_like_param,PDO::PARAM_STR);

$ si_gl_group_id变量可能为空。
在我的HTML中是这样的：

<option value="">All</option>
<option value="0">Zero</option>
<option value="1">One</option>

当我在phpmyadmin上执行此查询时，它可以工作，但在脚本中却不起作用。

最佳答案

您应该使用concat concat('%', :si_group_id, '5')

所以
    $ si_like_param = $ si_gl_group_id;

$stmt = $db->prepare("select  m1.id, m1.name, m1.surname, m1.fathername
    , m1.region_num, m1.school_num,m1.variant,m1.sinif, m1.qrup,m1.f_lan
    from students_answers m1, results m2
    where m1.id_exam=:si_exam_id
        and m1.id=m2.st_answer_id
        and m2.result_level >= :si_min_score
  and m1.school_num in ('003','018','019','020')
  and m1.region_num = 20
  and m1.qrup like  concat('%', :si_group_id, '5')
        order by m2.result_level desc;");
                        $stmt->bindparam(":si_exam_id", $si_exam_id);
                        $stmt->bindparam(":si_min_score", $si_min_score);
                        $stmt->bindparam(":si_group_id", $si_like_param,PDO::PARAM_STR);

并且您不应该使用旧的隐式联接sintax，而应将显式联接sintax用作

 $stmt = $db->prepare("select  m1.id, m1.name, m1.surname, m1.fathername
    , m1.region_num, m1.school_num,m1.variant,m1.sinif, m1.qrup,m1.f_lan
    from students_answers m1
    INNER JOIN results m2  ON m1.id=m2.st_answer_id
    where m1.id_exam=:si_exam_id

        and m2.result_level >= :si_min_score
      and m1.school_num in ('003','018','019','020')
      and m1.region_num = 20
      and m1.qrup like  concat('%', :si_group_id, '5')
        order by m2.result_level desc;");
                        $stmt->bindparam(":si_exam_id", $si_exam_id);
                        $stmt->bindparam(":si_min_score", $si_min_score);
                        $stmt->bindparam(":si_group_id", $si_like_param,PDO::PARAM_STR);

关于php - 将空值传递给mysql一样的查询，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/53633255/