PostgreSQL SUM

The PostgreSQL SUM aggregate function returns the sum value of all rows in a select.

SELECT SUM(table_column)
FROM table_name;

id	good_type	name	description	price
1	A	Car_1	Car 1 description	100
2	A	Car_2	Car 2 description	200
3	A	Car_3	Car 3 description	100
4	B	Boat_4	Boat 4 description	500
5	B	Boat_5	Boat 5 description	300
6	C	Train_1	Train 123 description	800

SELECT SUM(price) 
FROM goods;

2000

SELECT good_type, SUM(price) sum_price
FROM goods
GROUP BY good_type;