database design - MySQL table for saving a quantity to a 1:M relationship -


i have tables called invoice, item , invoice_item. invoice item tables has invoice_id , item_id columns store 1:m type relationship, invoice can have many items.

now want somehow store information item quantity. suitable create invoice_item_quantity table, store invoice_id, item_id , invoice_item_quantity values, respectively? or there more optimal solution?

i over-engineering this, adding item_quantity column invoice table won't work cause can have many different types of items, there no context there.

i need way store model this:

  • invoice
    • item 1 x 5
    • item 2 x 2
    • item 3 x 15

how can optimally store quantities in model above?

i may misunderstanding, sounds have many-to-many relationship between invoice , item tables, , using junction table support invoice_item table (this junction has one-to-many relationship both invoice , item).

if looking typical, normalized database design, storing quantity on invoice_item table good. idea make invoice id , item id compound primary key on junction table.


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