I am building an application that is using JSON / XML files to persist data. This is why I indicated “outside of SQL” in the title.
I understand one benefit of join tables is it makes querying easier with SQL syntax. Since I am using JSON as my storage, I do not have that benefit.
But are there any other benefits when using a separate join table when expressing a many-to-many relationship? The exact expression I want to express is one entity’s dependency on another. I could do this by just having a “dependencies” field, which would be an array of the IDs of the dependencies.
This approach seems simpler to me than a separate table / entity to track the relation. Am I missing something?
Feel free to ask for more context.
Conceptually, the benefit of a join table is to allow many-to-many relations. That’s it.
If I understand you correctly, your relations are one-to-many, so a join table would just be needless complexity.
And to cover atomicity. Child records deleted when a parent record is, etc.
The list would still allow a many-to-many relationship. Let demonstrate:
entity A and entity B both have 2 members: A-1, A-2, B-1, and B-2.
we add a “relations” field to entity A, which is a list of IDs from B, describing the list of B’s that A is related to.
A-1 has the relations field as:
[B-1, B-2]and A-2 has[B-1, B-2].As you can see, this is a many-to-many relationship. Each of our entities is tied to multiple entities. So this is many on both sides, hence many to many
That’s overly complicated to my eyes, and not really relevant. The point I was trying to make is just that a join table is unnecessary in the situation you originally described.
What I described in the comment above is the same thing I originally described, but expanded.
A dependency relation can still be many to many (and in my case, it is). The comment above gives an example to prove it.