postgresql - Build SQL query with JOIN and limits -


help me please build postgresql query. there 2 tables: products(id, title) , prices(id, product_id, price_type, moment, value)

moment - timestamp, can in past or future

assume price_type has 2 option: retail or purchase

but 1 product may has many retail prices different moments.

i need select products actual retail , purchase prices, moment less now.

it's can done

select        products.id,        products.title_translations title,       retail_prices.moment ret_moment,       pur_prices.value purchase,       retail_prices.value retail products  left outer join prices pur_prices on products.id=pur_prices.product_id , pur_prices.price_type='purchase' , pur_prices.moment<current_timestamp left outer join prices retail_prices on products.id=retail_prices.product_id , retail_prices.price_type='retail' , retail_prices.moment<current_timestamp order products.id;

it works, returns product prices, need last prices(by moment).

just use row_number find last price before current time

with last_prices (     select            products.id,            products.title_translations title,           prices.moment,           prices.value,           prices.price_type,           row_number() on (partition product_id, price_type                               order moment desc) rn     products      left join prices       on products.id = prices.product_id      moment < now()    ) select id, title,         max(case when price_type = 'retail'                 moment            end) retail_moment,        max(case when price_type = 'retail'                 value            end) retail_price,        max(case when price_type = 'purchase'                 moment            end) purchase_moment,        max(case when price_type = 'purchase'                 value            end) purchase_price last_prices      rn = 1 group id, title order id

Comments

Post a Comment

Popular posts from this blog

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

angular - DownloadURL return null in below code -

when change file updated in firebase storage when try downloadurl show null. filechange(event: any) { const imagefolder: string = this.employee.id; const filelist: filelist = event.target.files; const file: file = filelist[0]; const storageref = firebase.storage().ref().child(`${imagefolder}/profile.jpg`).put(file); console.log(storageref.snapshot.downloadurl); } the put() asynchronous. if want url after file uploaded have this: firebase.storage().ref().child(`${imagefolder}/profile.jpg`).put(file).then((snapshot) => { storageref = snapshot.downloadurl: console.log(snapshot.downloadurl); });
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