Question

Consider the following tables:

Table 1: PRODUCTS

This table stores the basic details of the products available in a shop.

PID	PName	Category
201	Laptop	Electronics
202	Chair	Furniture
203	Desk	Furniture
204	Smartphone	NULL
205	Tablet	Electronics

Table 2: SALES

This table records the number of units sold for each product.

SaleID	PID	UnitesSold
301	201	50
302	202	100
303	203	60
304	204	80
305	205	70

Write SQL queries for the following:

1. To delete those records from table SALES whose UnitsSold is less than 80.
2. To display names of all products whose category is not known.
3. To display the product names along with their corresponding units sold.

Answer 1

1. DELETE FROM SALES WHERE UNITSSOLD < 80;
2. SELECT PNAME FROM PRODUCTS WHERE CATEGORY IS NULL;
3. SELECT P. PNAME, S.UNITSSOLD FROM PRODUCTS P JOIN SALES S ON P.PID = S.PID;