Data preparation for the database

[zxuanxu]

We need to prepare the data for the database based on the ERD we defined and the user stories we tried to tell.

• [x] Import initial data into MongoDB
• [x] Extract user's daily activity details from the initial data and store it in another collection called dailyActivityDetails
• [x] Extract user's daily activity summary by category from the initial data and store it in another collection called dailyActivitiesSummary