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use existing database instead of django database

i want to connect my existing database of sql server with django but the problem is django has its model which create its own database but i dont want to create database using django i just want to use mine to retrieve data.
the one solution i saw was to use inspectdb but hte problem with inspectdb is that it does not pick wring keys and constraints sometime plus have to set many thing manually but in my project my database is user defined user will connect its database so i dont actually know that how many and what table user's database have do i just want to connect that database with django and use the value of it.
my existing database is sqlserver.
any technique to use my existing database without using django database and retrive data from existing database.
thankyou.

As you mentionned, you should use : inspectdb to create your models as stated in the doc (https://docs.djangoproject.com/en/4.0/howto/legacy-databases/)
Setting the managed option to False in the Meta class of model, you can instruct Django to not make any migrations or database schema modification, but you need to tweak the model yourself to ensure every kind of mapping is as you intendend, and obviousl ensure coherence between your DB schema and models.

Handling many-to-many relationship from existing database using Django ORM

I'm starting to work with Django, already done some models, but always done that with 'code-first' approach, so Django handled the table creations etc. Right now I'm integrating an already existing database with ORM and I encountered some problems.
Database has a lot of many-to-many relationships so there are quite a few tables linking two other tables. I ran inspectdb command to let Django prepare some models for me. I revised them, it did rather good job guessing the fields and relations, but the thing is, I think I don't need those link tables in my models, because Django handles many-to-many relationships with ManyToManyField fields, but I want Django to use that link tables under the hood.
So my question is: Should I delete the models for link tables and add ManyToManyFields to corresponding models, or should I somehow use this models?
I don't want to somehow mess-up database structure, it's quite heavy populated.
I'm using Postgres 9.5, Django 2.2.

In many cases it doesn't matter. If you would like to keep the code minimal then m2m fields are a good way to go. If you don't control the database structure it might be worth keeping the inspectdb schema in case you have to do it again after schema changes that you don't control. If the m2m link tables can grow properties of their own then you need to keep them as models.

Django model creation from existing MongoDB databases

I have a few databases in MongoDB that I want to create models for dynamically, since there are many databases and I cannot do it manually. Questions:
What should my models.py look like? (Does inspectdb work with mongodb databases or only SQL based dbs?)
Since the database models are created dynamically, how do I code the serializer class to return the dynamic fields?
Thanks in advance.

Django supports an object-relational mapper, that is aimed at traditional relational databases. While there are a number of mongodb packages for Django, none of them support inspectdb to construct your models. Either way, inspectdb is a kludge designed as a one of process to help a one-of migratation away from a legacy system, i.e. you'd build your models.py file once and never run inspectdb again. This is not what you want to do, as you seem to want dynamic models that can be added or altered at runtime.
On the bright side, Django MongoDB Engine has some support for arbitrary embedded models within pre-defined models. But even then they don't seem too supportive of it:
As you can see, generic embedded models add a lot of overhead that bloats up your data records. If you want to use them anyway, here’s how you’d do it...
In summary, try to build your models as best you can to actually match your requirements. If you know nothing about your models ahead of production, then perhaps Django isn't the right solution for you.

Database Tables not defined in DJANGO models

Is it fine not to define table stucture in models.py...I mean we are using
cursor.execute('some query')
so its okay not to make something like this :
def tblNew(models.Model)
col1 = models.CharField(max_length=2)
Thanks for guidance, Im a newbie in django.

You CAN create database tables directly in postgresql But you'd have to create models.py files later because otherwise you will be missing out on several things. If you have pre-existing database, then you have django-admin.py command to pick them up for you (https://docs.djangoproject.com/en/dev/ref/django-admin/#inspectdb)
ORM. It makes alot of things easyer. Writing sql in views? Why would that be good? Because that is what you get if you do not use ORM at all. And while i do have sql in some of my views, it only exists there because django lacks some features like language collation specific sorting. But otherwise writing sql in views hampers readability.
You can't use database migrations. South (http://south.aeracode.org/) is one awesome project that most big django projects use. In fact i think it was most used django project in some apps poll. Django 1.7 will provide the migrations too, but you will need to declare models im models.py for that. What you loose if you do not use database migrations - SANITY. I do not exaggerate here. Keeping track of database changes in development and prelive/live servers is nightmare otherwise.
Also is not using django ORM in some places (not declaring models) kind of strange, while you will definately use django models and ORM elsewhere - or will you stop using django authentication, sessions and site logic also? All those use django ORM...

Using 'old' database with django

I'm using a hand built (Postgres) database with Django. With "inspectdb" I was able to automatically create a model for it. The problem is that some tables have multiple primary keys (for many-to-many relations) and they are not accessible via Django.
What's the best way to access these tables?

There is no way to use composite primary keys in Django's ORM as of now (up to v1.0.2).
I can only think of three solutions/workarounds:
There is a fork of django with a composite pk patch at github that you might want to try.
You could use SQLAlchemy together with Django.
You have to add a single field primary key field to those tables.

Django does have support for many-to-many relationships. If you want to use a helper table to manage this relationships, the ManyToManyField takes a through argument which specifies the table to use. You can't model anything terribly complex this way, but it is good for most simple applications.