FILTER clause

Learn the FILTER keyword.

The FILTER clause makes an aggregate conditional. More readable than CASE.

SELECT
  SUM(amount) FILTER (WHERE category = 'Kitap') AS Kitap,
  SUM(amount) FILTER (WHERE category = 'Elektronik') AS Elektronik
FROM sales;

Supported by PostgreSQL and SQLite.

SUM(amount) FILTER (WHERE category = 'Kitap') AS Kitap, … is selected from sales.

FILTER clause — details

FILTER goes after the aggregate. It gives conditional sums without writing CASE.

FILTER is supported in PostgreSQL and SQLite; MySQL lacks it, so there you get the same result with SUM(CASE WHEN … THEN amount END).

Write a conditional sum with SUM(amount) FILTER (WHERE category = 'Kitap').

Show example solution

SELECT
  SUM(amount) FILTER (WHERE category = 'Kitap') AS Kitap,
  SUM(amount) FILTER (WHERE category = 'Elektronik') AS Elektronik
FROM sales;

Add FILTER

SUM(amount) ____ (WHERE category = 'Kitap') AS Kitap

Show answer

SUM(amount) FILTER (WHERE category = 'Kitap') AS Kitap

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