A. Preliminary Your Approach First and foremost, I must commend your attitude. It is rare to find someone who not only thinks and works from a solid grounding, and who wishes to understand and implement a Double-Entry Accounting system, instead of: either not implementing DEA, thus suffering multiple re-writes, and pain at each increment, each … Read more
You would use MongoDB when you have a use case that matches its strengths. Do you need a schema-less document store? Nope, you have a stable schema. Do you need automatic sharding? Nope, you don’t have extraordinary data needs or budget for horizontally scaling hardware. Do you need map/reduce data processing? Not for something like … Read more
As always: there is no best solution. Each solution makes different things easier or harder. The right solution for you depends on which operation you will do most. Naive Approach with parent-id: Pros: Easy to implement Easy to move a big subtree to another parent Insert is cheap Needed Fields directly accessible in SQL Cons: … Read more
Candidate Key – A Candidate Key can be any column or a combination of columns that can qualify as unique key in database. There can be multiple Candidate Keys in one table. Each Candidate Key can qualify as Primary Key. Primary Key – A Primary Key is a column or a combination of columns that … Read more
This is just 2 different APIs written by regular people. Difference is in syntax of commands and maybe in performance, just install both, make your own tests for your goals and choose one you think is more suitable for you. Here is a comparison by NPMCompare:
What you need to consider when designing tables is not necessarily what they’ll have access to and how that is similar/dissimilar, but rather how the user levels themselves are similar/dissimilar. For example, if the user types will have the same attributes (name, email, birthdate, etc), then they belong in one table together with a column … Read more
Assuming you have a relation, A, with a single attribute, ‘a’ (reducing a more complex relation to this is a simple task in relational algebra, I’m sure you got this far), so now you want to find the maximum value in A. One way to do it is to find the cross product of A … Read more
Other answers have ably outlined the pros and cons of your various options. I believe that your Option 1 (property bag) is the best overall design for most applications, especially if you build in some protections against the weaknesses of propety bags. See the following ERD: In the above ERD, the USER_SETTING table is very … Read more
CASCADE will propagate the change when the parent changes. (If you delete a row, rows in constrained tables that reference that row will also be deleted, etc.) SET NULL sets the column value to NULL when a parent row goes away. RESTRICT causes the attempted DELETE of a parent row to fail. EDIT: You didn’t … Read more
I will summarize my thoughts from my blog post – A lesson in address storage (on archive.org). On my current project [I work for a logistics company] we’re storing international addresses. I’ve done research on addresses all over the world in the design of this portion of the database. There’s a lot of different formats. … Read more