mysql - One to one relationship with foreign key to mutiple tables -


please let me start saying, know has been asked many times before , i've studied other questions (and answers) after 2 days of reading questions , amending database can't work want.

at moment have various tables, example customer, supplier, product, banner, etc.

i have table called custom_field allows custom fields created , used against various other tables.

at moment of tables this:

general tables ==============  customer +-------------+---------------+ | customer_id | customer_name | +-------------+---------------+ | 1           | peter         | | 2           | sally         | +-------------+---------------+  banner +-----------+-------------+--------------+ | banner_id | banner_name | banner_width | +-----------+-------------+--------------+ | 1         | easter      | 100px        | | 2         | xmas        | 250px        | +-----------+-------------+--------------+  tables managing custom fields =================================  custom_field +----------+------------+----------------+-----------+ | field_id | field_name | field_label    | item_type | +----------+------------+----------------+-----------+ | 100      | fav_color  | favorite color | customer  | | 101      | border     | border         | banner    | +----------+------------+----------------+-----------+  custom_field_value +----------+----------+---------+-------------+ | value_id | field_id | item_id | field_value | +----------+----------+---------+-------------+ | 1567     | 100      | 1       | red         | | 1568     | 100      | 2       | blue        | | 1569     | 101      | 1       | solid       | | 1570     | 101      | 2       | dotted      | +----------+----------+---------+-------------+

to clarify, item_id refers customer_id, banner_id, or supplier_id, etc. in example above means peter has "favorite color" custom field set red, , sally has "favorite color" custom field set blue.

the easter banner has "border" custom field set solid, , xmas banner has "border" custom field set dotted.

this works fine, except there can no foreign key or referential integrity set between custom_field_value.item_id , customer.customer_id (or banner.banner_id) because item_id's context described item_type field in custom_field table.

i don't want create multiple nullable foreign keys (not sure work anyway) become unmanageable.

i did try creating sub tables, example customer_custom_field, , relate between customer , custom_field, again becomes unmanageable when consider every table potentially have custom fields.

a single field value ever apply single entity table.

as aside want create attachments table managing uploaded attachments particular entity, , again apply customers, suppliers, products , various other tables, it's similar issue.


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

performance - Why is XCHG reg, reg a 3 micro-op instruction on modern Intel architectures? -

i'm doing micro-optimization on performance critical part of code , came across sequence of instructions (in at&t syntax): add %rax, %rbx mov %rdx, %rax mov %rbx, %rdx i thought had use case xchg allow me shave instruction , write: add %rbx, %rax xchg %rax, %rdx however, dimay found agner fog's instruction tables , xchg 3 micro-op instruction 2 cycle latency on sandy bridge, ivy bridge, broadwell, haswell , skylake. 3 whole micro-ops , 2 cycles of latency! 3 micro-ops throws off 4-1-1-1 cadence , 2 cycle latency makes worse original in best case since last 2 instructions in original might execute in parallel. now... cpu might breaking instruction micro-ops equivalent to: mov %rax, %tmp mov %rdx, %rax mov %tmp, %rdx where tmp anonymous internal register , suppose last 2 micro-ops run in parallel latency 2 cycles. given register renaming occurs on these micro-architectures, though, doesn't make sense me done way. why wouldn't register renamer ...
Read more

c# - Asp.net web api : redirect unauthorized requst to forbidden page -

im trying redirect unauthorized request forbidden page instead i'm getting forbidden page in response body , how can fix ? here's startup class : app.createperowincontext(storecontext.create); app.createperowincontext<applicationusermanager>(applicationusermanager.create); app.createperowincontext<applicationsigninmanager>(applicationsigninmanager.create); app.usecookieauthentication(new cookieauthenticationoptions { authenticationtype = defaultauthenticationtypes.applicationcookie, expiretimespan = timespan.fromdays(30), }); app.useexternalsignincookie(defaultauthenticationtypes.externalcookie); app.usetwofactorsignincookie(defaultauthenticationtypes.twofactorcookie, timespan.fromminutes(5)); app.usetwofactorrememberbrowsercookie(defaultauthenticationtypes.twofactorrememberbrowsercookie); the method im trying reach : [httpget] [authorize(roles = "admin")] public string getcurrentusername() { return userman...
Read more