mysql - How to write a sql query -


i have 3 tables

quality

id    name ----------  1    bold  2    frank  3    quite  4    friendly

student 

id name ---------  1   2  b  3  c

studentquality

id  fk_qual  fk_stud  1   1        1  2   2        1  3   1        2  4   2        2  5   3        2  6   1        3  7   2        3  8   3        3  9   4        3

these tables. how students bold, frank , quite. if use in operation, 3 students, need 2 students if use bold, frank, should 3 students if use bold, frank, quite , friendly, should 1 students how query this.

you like:

  1. declaring table variable, holding values you're searching for
  2. selecting data , using table variable condition inner join , counting values of table variable , compare them amount of qualities

like:

declare  @qualities table(qname  varchar(100)); insert   @qualities           values ('bold'),('frank'),('quite');         select s.name          student s    inner join studentquality sq            on s.id = sq.fk_stud    inner join quality q            on sq.fk_qual = q.id           , q.name in (select qname @qualities)                 group s.name       having count(*) = (select count(qname) @qualities)

Comments

Post a Comment

Popular posts from this blog

Is there a better way to structure post methods in Class Based Views -

i'm using class based views in django , never specify url in ajax calls , omit action parameter in form because know these requests go through post method of class based view. notice view - profile page make many requests depending on user updating on page - post method become convoluted , if/else mess example: def post(self, request, *args, **kwargs): # handle user changing available date if request.post.get('availabledate') != none: self.updateavailabledate(request) return jsonresponse({'result':'success'}) if request.post.get('newprojectname') != none: creative_user = creativeuserprofile.objects.get(id = request.user.id) project = project.create_project(creative_user, request.post['newprojectname']) project.save() return jsonresponse({'projectid': project.id }) if request.post.get('projectimage') != none , request.files['file']: proj...
Read more

What is happening when Matlab is starting a "parallel pool"? -

running parallel cpu processes in matlab starts command parpool() according documentation , function: [creates] special job on pool of workers, , [connects] matlab client parallel pool. this function takes bit of time execute, on order of 30 seconds. in other multi-cpu paradigms openmp, parallel execution seems totally transparent -- i've never noticed behavior analogous matlab (granted i'm not experienced parallel programming). so, happening between time parpool() called , when finishes executing? takes long? parallel computing toolbox enables run matlab code in parallel using several different paradigms (e.g. jobs , tasks, parfor , spmd , parfeval , batch processing), , run either locally (parallelised across cores in local machine) or remotely (parallelised across machines in cluster - either 1 own, or 1 in cloud). in of these cases, code run on matlab workers , copies of matlab without interactive desktop. if you're intending run on remo...
Read more

php - Cannot override Laravel Spark authentication with own implementation -

during login process of laravel spark need request token of remote api. api stores exact same users , passwords laravel spark application. therefore need username , non hashed password of user during authentication process. i thought overriding authenticated method solution problem. in routes/web.php override post /login endpoint , pointing endpoint own logincontroller: <?php namespace app\http\controllers\auth; use illuminate\support\facades\log; use illuminate\http\request; use laravel\spark\http\controllers\auth\logincontroller sparklogincontroller; class logincontroller extends sparklogincontroller { /** * create new login controller instance. * * @return void */ public function __construct() { parent::__construct(); } /** * handle successful authentication attempt. * * @param request $request * @param \illuminate\contracts\auth\authenticatable $user * @return response */ public fu...
Read more