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Pivot rows to columns

MediumP2Coding

Table sales:

Column	Type
product	text
quarter	int (1 to 4)
amount	int

A product can have several rows for the same quarter. Turn quarters into columns: one row per product with the total sales of each quarter. A quarter without sales is 0.

Output columns: product, q1, q2, q3, q4.

Schema

CREATE TABLE sales (
  product text NOT NULL,
  quarter int NOT NULL CHECK (quarter BETWEEN 1 AND 4),
  amount int NOT NULL
);

Example 1

Input: sales: (pen, 1, 10), (pen, 1, 5), (pen, 3, 7)
Output: pen: q1 15, q2 0, q3 7, q4 0

Constraints

PostgreSQL dialect.

Hints

PostgreSQL

Run checks the 3 visible tests, Submit all 5. ⌘Enter runs, ⌘⇧Enter submits.