SQL practice: Tables, Types and Constraints

Write the statement adding a CHECK that order_items.quantity must be above 0.

Write the statement adding an email column to customers.

Create a table suppliers with an auto ID, a name that can't be blank, a city, and a rating between 0 and 5.

Add a DEFAULT of 'Pending' to orders.status. (Write the ALTER.)

Which type would you choose for: a phone number, an invoice total, a delivery date, a "is active" flag? Justify the phone number one.

Write a CHECK making sure products.unit_price is never below cost_price.

Explain what would go wrong if orders.customer_id had no foreign key constraint.

Create a temporary table named temp_lead_stage with two columns: lead_id (INT) and lead_score (NUMERIC(5,2)).