使用 sql 查询结果作为新 sql 语句的搜索词

Question

So I am trying to use a result from an SQL search $search_course and then having that as the WHERE LIKE part of the next statement $Search_Module .

once the $Search_Module query has finished I would like the results to be in a list which I know should be coded correctly.

I have tried the following code but the search returns no values;

Any help with this would be much appreciated, thanks in advance.

        $search_course = "
    SELECT title, id, wyl, overview, module, course, careers
    FROM course
    LEFT JOIN cm
    ON course.id=cm.course
    WHERE id LIKE '%".$_POST['submitcourseselection']."%'";

    $result = $mysqli->query($search_course) or die($mysqli->error);
    $display_course = $result->fetch_assoc();

    //Searches the module table in the DB for modules within the course
    $Search_Module = "
    SELECT id, title, level, credits
    FROM module
    WHERE id LIKE '".$search_course['module']."'";

    $M_Results = $mysqli->query($Search_Module) or die($mysqli->error);


    $ModuleList = '';
    while ($MResults = $M_Results->fetch_assoc()) {
        $ID = $MResults['id'];
        $Title = $MResults['title'];
        $Level = $MResults['level'];
        $Credits = $MResults['credits'];
        $ModuleList.='<div><h2>'.$Title.'</h2></div>'; 
    }

Answer 1

you don't need LIKE in your second query and you can do all by one query.

    $search_course = "
        SELECT id, title, level, credits
        FROM module
        WHERE id IN (SELECT module
        FROM course
        LEFT JOIN cm
        ON course.id=cm.course
        WHERE id LIKE '%".$_POST['submitcourseselection']."%'")";

Answer 2

in your where clause WHERE id LIKE '".$search_course['module']."'"; , you are referencing an array location of a string $search_course , which is your SQL statement.

I think you meant to reference your result array $display_course , so try this:

$search_course = "
SELECT title, id, wyl, overview, module, course, careers
FROM course
LEFT JOIN cm
ON course.id=cm.course
WHERE id LIKE '%".$_POST['submitcourseselection']."%'";

$result = $mysqli->query($search_course) or die($mysqli->error);
$display_course = $result->fetch_assoc();

//Searches the module table in the DB for modules within the course
$Search_Module = "
SELECT id, title, level, credits
FROM module
WHERE id LIKE '".$display_course['module']."'";

$M_Results = $mysqli->query($Search_Module) or die($mysqli->error);


$ModuleList = '';
while ($MResults = $M_Results->fetch_assoc()) {
    $ID = $MResults['id'];
    $Title = $MResults['title'];
    $Level = $MResults['level'];
    $Credits = $MResults['credits'];
    $ModuleList.='<div><h2>'.$Title.'</h2></div>'; 
}