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 |