如何使用传统的关系数据库复制核心数据模型？

Question

I have my app using core data with the data model below. However, I'm switching to a standard database with columns and rows. Can anyone help me with setting up this new database schema?

Answer 1

First of all you need to create tables for each of the Entities and their attributes (note I added "id" to each of the tables for relationships):

1. Routine (name, timestamp, id)
2. Exercise - this looks like a duplicate to me, so leaving one only here (muscleGroup, musclePicture, name, timeStamp, id)
3. Session (timeStamp, id)
4. Set (reps, timeStamp, unit, weight, id)

Now that you have tables that describe each of the entities, you need to create tables that will describe the relationships between these entities - as before table names are in capitals and their fields are in parenthesis:

1. RoutineExercises (routine_id, exercise_id)
2. SessionExercises (session_id, exercise_id)
3. ExerciseSets (exercise_id, set_id)

That's it! Now if you need to add an exercise to a routine, you simply:

1. Add an entry into Exercise table
2. Establish the relationship by adding a tuple into RoutineExercises table where routine_id is your routine ID and exercise_id is the ID of the newly created entry in the Exercise table

This will hold true for all the rest of the relationships.

NOTE: Your core data model has one-to-many and many-to-many relationships. If you want to specifically enforce that a relationship is one-to-many (eg Exercise can only have 1 routine), then you will need to make "exercise_id" as the index for the RoutineExercises table. If you want a many-to-many relationships to be allowed (ie each exercise is allowed to have multiple routines), then set the tuple of (routine_id, exercise_id) as the index.