Aggregates

Group By

Totals Per Category

GROUP BY runs aggregates separately for each group.

Program

Play the query to summarize sales per item.

group_by.sql 
CREATE TABLE sales (item TEXT, qty INTEGER);
INSERT INTO sales VALUES ('book', 2), ('pen', 5), ('book', 3);
SELECT item, SUM(qty) AS sold FROM sales GROUP BY item ORDER BY item;
GROUP BY `GROUP BY item` creates one group per item value.
aggregate per group `SUM(qty)` runs inside each group.
ORDER BY Sorting makes grouped output easy to compare.