Database and java

• Be wary of using ORMs and use the simplest tool (which might be using plain sql)

• Sql is a declarative language, and is not hard to learn. Very useful for working with relational databases

• Dont be too quick to go straight to modelling tables as objects and using ORMs, when calling a sql is a simpler

  • Using ORMs means a lot set up and code (more code, more chance of bugs), learning a DSL, testing, relying on the ORM to generate non efficient queries,

• Benefits of using Sql

  • We don’t need a new table for the join output, so we don’t create one.

    • The biggest failing of applied object-oriented programming has been the belief that you should faithfully reproduce your domain model in code.

    • In reality, a few core type definitions are useful for encapsulation and understanding, but tuples, sets, arrays, and so forth are all we need the rest of the time.

    • Unnecessary classes become a burden as the code evolves.

  • The query is declarative

    • Nowhere does it tell the database how to do the query; it just states the relational constraints the database must satisfy

    • Doing this in java (exp pre version 8), it would be done imperatively

    • Instead, we should declare constraints and desired outcomes, and then isolate the how implementation in one place or delegate to a library that can implement it for us

  • The database is more efficient at running the query then letting the code run query on the whole dataset

  • The domain-specific language (DSL) is well matched to the problem

    • SQL is mature, and well known, with lots of resources