SQL aggregate functions

Link: SQL

COUNT §

COUNT(...)

-- check how big the dataset is
SELECT COUNT(*) FROM product_spend;

COUNT DISTINCT §

COUNT(DISTINCT x): a bit different compare to SELECT DISTINCT in SQL SELECT

SELECT category, COUNT(DISTINCT user_id) FROM trades
GROUP BY category

SUM §

SUM(...)

SELECT COUNT(drug), SUM(total_sales) FROM pharmacy_sales
WHERE manufacturer = 'Pfizer';

AVG §

AVG(...)

MIN §

MIN(...)

MAX §

MAX(...)