SQL practice: CASE WHEN: If/Else Inside a Query

Label employees 'Senior' if salary ≥ 80000, else 'Junior'.

Label orders 'Done' if status is Delivered, else 'Not Done'.

Label products 'Thick' if thickness is 4.0 or more, 'Thin' if less, and 'Not a sheet' if thickness is empty.

Give each branch a label by region: North → 'Up North', South → 'Down South', everything else → 'Other'.

For each product, show a margin_health column: 'Good' if profit (price − cost) is above 700, 'OK' if above 400, else 'Thin'.

For each customer, show 'Old customer' if they signed up before 2019, 'Newer' otherwise, and 'Unknown' if the date is empty. (Order your WHENs carefully.)

Show each employee with a band column: '80k+', '40k-80k', or 'under 40k'.

Label each product 'Premium' (3000 or more), 'Standard' (1000 or more) or 'Budget'. No product ever comes out Premium. Fix it.