我在laravel
中有一个查询,它运行良好。
$subjects = $app->db->table('subjects')->LeftJoin('downloads', 'subjects.subjectID', '=', 'downloads.subject_id')
->where('universityID', $currentUser->universityID)->where('semesterID', $currentUser->semesterID)->where('courseID', $currentUser->courseID)
->select('subjects.subjectID', 'subjects.subjectName', 'subjects.price', 'downloads.is_download' )
->orderBy('subjectID')
->get();
当表中没有相关条目时,is_download
会变成null,这是唯一的问题。经过一些研究,我发现有一个函数IFNULL
,可以使用它来将is_download
的null
更改为0
。所以这是我的查询,但它不起作用,只显示空白屏幕。
$subjects = $app->db->table('subjects')->LeftJoin('downloads', 'subjects.subjectID', '=', 'downloads.subject_id')
->where('universityID', $currentUser->universityID)->where('semesterID', $currentUser->semesterID)->where('courseID', $currentUser->courseID)
->select('subjects.subjectID', 'subjects.subjectName', 'subjects.price', IFNULL( `downloads`.`is_download` , 0 ) )
->orderBy('subjectID')
->get();
我能在phpmyadmin中编写这个查询,但不知道如何在Laravel
中编写。
这是API,所以整个代码看起来像:
use Illuminate\Database\Query\Expression as raw;
use project\Models\Subject;
use project\Models\Semester;
use project\Models\StudentRegistration;
$app->get('/api/getSubject/:studentID', function($studentID) use ($app) {
error_reporting(E_ALL);
$currentUser = StudentRegistration::where('studentID', $studentID)->first();
$subjects = $app->db->table('subjects')->LeftJoin('downloads', 'subjects.subjectID', '=', 'downloads.subject_id')
->where('universityID', $currentUser->universityID)->where('semesterID', $currentUser->semesterID)->where('courseID', $currentUser->courseID)
->select('subjects.subjectID', 'subjects.subjectName', 'subjects.price', IFNULL( `downloads`.`is_download` , 0 ) )
->orderBy('subjectID')
->get();
print_r($subjects);
return $app->response->write(json_encode([
'error' => 0,
'subjects' => $subjects
]));
});