// Creating tables
Table users as U {
id int [pk, increment] // auto-increment
full_name varchar
created_at timestamp
country_code int
}

Table countries {
code int [pk]
name varchar
continent_name varchar
}

// Creating references
// You can also define relaionship separately
// > many-to-one; < one-to-many; - one-to-one Ref: U.country_code > countries.code
Ref: merchants.country_code > countries.code

//----------------------------------------------//

//// -- LEVEL 2
//// -- Adding column settings

Table order_items {
order_id int [ref: > orders.id] // inline relationship (many-to-one)
product_id int
quantity int [default: 1] // default value
}

Ref: order_items.product_id > products.id

Table orders {
id int [pk] // primary key
user_id int [not null, unique]
status varchar
created_at varchar [note: 'When order created'] // add column note
}

//----------------------------------------------//

//// -- Level 3
//// -- Enum, Indexes

// Enum for 'products' table below
Enum products_status {
out_of_stock
in_stock
running_low [note: 'less than 20'] // add column note
}

// Indexes: You can define a single or multi-column index
Table products {
id int [pk]
name varchar
merchant_id int [not null]
price int
status products_status
created_at datetime [default: `now()`]

Indexes {
(merchant_id, status) [name:'product_status']
id [unique]
}
}

Table merchants {
id int
country_code int
merchant_name varchar

"created at" varchar
admin_id int [ref: > U.id]
Indexes {
(id, country_code) [pk]
}
}

Table merchant_periods {
id int [pk]
merchant_id int
country_code int
start_date datetime
end_date datetime
}