在 Laravel 中使用 IFNULL
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use IFNULL in laravel
提问by Kapil Sharma
I have a query in laravelwhich is working fine.
我有一个laravel工作正常的查询。
$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();
There is only one issue that is_downloadcomes null when there is no relative entry in table. After some research I found that there is a function IFNULLby using which I can change is_downloadnullto 0. So here is my query which is not working. Blank screen is showing.
is_download当表中没有相对条目时，只有一个问题为空。经过一些研究，我发现有一个函数IFNULL可以使用，我可以将其更改is_downloadnull为0. 所以这是我的查询不起作用。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();
I am able to write this query in my phpmyadmin but not know how to write in laravel
我可以在我的 phpmyadmin 中编写此查询，但不知道如何编写 laravel
This is the api, So whole code looks like
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
]));
});
回答by Md Mahfuzur Rahman
Try like this:
像这样尝试：
DB::Raw('IFNULL( `downloads`.`is_download` , 0 )');
$subjects = $app->db->table('subjects')->LeftJoin('downloads', 'subjects.subjectID', '=', 'downloads.subject_id')
->where('universityID', $currentUser->universityID)->where('semesterID', $currentUser->semesterID)->where('courseID', $currentUser->courseID)
->select('subjects.subjectID', 'subjects.subjectName', 'subjects.price', DB::Raw('IFNULL( `downloads`.`is_download` , 0 )') )
->orderBy('subjectID')
->get();
回答by Dayachand Patel
You just need to use like this way,
你只需要像这样使用，
DB::raw('IFNULL( downloads.is_download, 0) as is_download')
回答by Agus Suhardi
This my code
这是我的代码
->whereRaw('customer_id = IFNULL(?, customer_id)', [$request->customer_id])
