Users

Column Name	Data Type	Details
id	integer	not null, primary key, unique
first_name	string	not null
last_name	string	not null
email	string	not null, indexed, unique
img_url	string	not null
password_digest	string	not null
session_token	string	not null, indexed, unique
phone_number	string	not null, indexed, unique
card_digest	string	indexed
updated_at	datetime	not null
created_at	datetime	not null

• a user has many balances

Coins

Column Name	Data Type	Details
id	integer	not null, primary key, unique
name	string	not null, unique
ticker_symbol	string	not null, unique
price	float	not null
updated_at	datetime	not null
created_at	datetime	not null

Transactions

Column Name	Data Type	Details
id	integer	not null, primary key, unique
date	datetime	not null
user_id	integer	not null, indexed, foreign_key
coin_id	integer	not null, indexed, foreign_key
amount	float	not null
updated_at	datetime	not null
created_at	datetime	not null

• the user_id and coin_id point to users and coins respectively
• each user and each coin have many transactions and each transaction belongs to both a coin and a user
• like balances, this is essentially a joins table between users and coins, but this also includes dates, to keep track of a history of transactions