PL/SQL Group By

The Group By clause is used when an aggregate function (count, max, min, sum, avg) exists in the pl/sql query.

SQL Query

SELECT c.course_id, c.name, c.description, o.order_id, c.price
FROM course c, orders o
WHERE o.course_id = c.course_id;

Output

COURSE_ID	NAME	DESCRIPTION	ORDER_ID	PRICE
1	SQL 1	SQL course for beginners	22	10
1	SQL 1	SQL course for beginners	1	10
4	PHP	PHP course	3	75
5	CSS	Learn CSS	21	20
5	CSS	Learn CSS	2	20

Group By example

 
SELECT c.course_id, c.name, c.description, c.price, 
		SUM(c.price) AS amount, COUNT(c.course_id) AS quantity
FROM course c, orders o
WHERE o.course_id = c.course_id
GROUP BY c.course_id, c.name, c.description, c.price;

Output

COURSE_ID	NAME	DESCRIPTION	PRICE	AMOUNT	QUANTITY
1	SQL 1	SQL course for beginners	10	20	2
4	PHP	PHP course	75	75	1
5	CSS	Learn CSS	20	40	2

↑