How to model this relationship efficiently - sql

Question

I have an Exercise table, each Exercise can be 1 of 5 Exercise Type (eg. cardio, timed activity, weights, combination of weights and timed, something else). Each of the different types stores the data in a different manner (eg. cardio is intensity and time, timed is just time in minutes, weights is sets x reps x weight, and something else could be something else).
So its a given that I have an Exercise table, but not sure how to model the Exercise Type and store the associated exercise data for each exercise type. Each Exercise will be of only one Exercise Type and each Exercise Type can belong to many Exercises.
I was leaning towards just an Exercise table and an Exercise Type table and have a many to one relationship, but I can't figure out how best to store each exercises data.
This is going to be modeled for Entity Framework 6 and MS SQL Server.

Answer 1

I think your scenario is good for Inheritance (using Table-per-Hierarchy), here is my suggested design:
public Exercise
{
public int ExerciseId {get;set;}
[ForeignKey("ExerciseBaseTypeId")]
public ExerciseBaseType ExerciseType {get;set;}
[Required]
public int ExerciseBaseTypeId {get;set;}
}
public ExerciseBaseType
{
public int BaseTypeId{get;set;}
public Link<Exercise> Exercises {get;set;}
//put other base properties that is common to all exercise types
}
public Cardio : ExerciseBaseType {
public string Intensity {get;set;}
public int Time {get;set;}
}
public Timed : ExerciseBaseType {
public int Duration {get;set;}
}
public Weight : ExerciseBaseType {
public int Sets {get;set;}
public int Weight {get;set;}
}
Here is your dbcontext file:
public class ExerciseDbContext : DbContext
{
public ExerciseDbContext()
: base("ExerciseDatabase"){ }
}
public DbSet<Exercise> Exercises { get; set; }
public DbSet<ExerciseBaseType> ExerciseTypes { get; set; }
protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
modelBuilder.Entity<Exercise>()
.HasRequired(e => e.ExerciseBaseType)
.WithMany(ebt => ebt.Exercises)
.HasForeignKey(e.ExerciseBaseTypeId);
}
As an example, lets add a Timed Exercise and attach it to the exercise with id #1:
ExerciseDbContext db = new ExerciseDbContext();
var timedExercise = new Timed();
timedExercise.Duration = 60;
//set the other base properties
db.Exercises
.Single(e => e.ExerciseId = 1)
.ExerciseTypes.Add(timedExercise);
db.SaveChanges();
Does this make sense?