将空值传递给mysql一样的查询

Question

My SQL is like that:

$si_like_param="%".$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);

it is possible that this variable $si_gl_group_id comes null. in my HTML it is like that:

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

when I execute this query on phpmyadmin it works but in script it didn't work.

Answer 1

You should use a concat concat('%', :si_group_id, '5')

so
$si_like_param=$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);

and you should not use old implict join sintax but explicit join sintax as

 $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);