There is a canonical exercise table that holds all the different types of exercises. ie Squats, Pushups, etc
When you build a workout, you add exercises from this table to the workout. However you could have the same exercise appear different times within the same workout and within the same program. So each time you add an exercise to a workout it gets a unique exercise id.
When viewing historical data it is useful to have to option to display an exercise by both the unique exercise id and also by the canonical exercise index from the exercises table. This way you can see all squats you've done across all workouts as well as just the squats from the first time you did squats for that specific workout.
There is a canonical exercise table that holds all the different types of exercises. ie Squats, Pushups, etc
When you build a workout, you add exercises from this table to the workout. However you could have the same exercise appear different times within the same workout and within the same program. So each time you add an exercise to a workout it gets a unique exercise id.
When viewing historical data it is useful to have to option to display an exercise by both the unique exercise id and also by the canonical exercise index from the exercises table. This way you can see all squats you've done across all workouts as well as just the squats from the first time you did squats for that specific workout.