Modulo and remainder

-- Function form (works on every major engine).
SELECT MOD(10, 3);                  -- 1
SELECT MOD(11, 3);                  -- 2
SELECT MOD(12, 3);                  -- 0

-- Operator form (Postgres / MySQL / DuckDB / SQL Server / SQLite).
SELECT 10 % 3;                      -- 1

-- Even / odd test.
SELECT id FROM users WHERE MOD(id, 2) = 0;  -- even ids
SELECT id FROM users WHERE id % 2 = 1;       -- odd ids

-- Bucketing: distribute rows into N evenly-sized buckets by hash.
SELECT id, MOD(ABS(HASH(id)), 10) AS bucket FROM users;

-- Sample 1% of rows reproducibly (no RANDOM — same rows every run).
SELECT * FROM ecom_events WHERE MOD(ABS(HASH(event_id)), 100) = 0;

-- Bucket users for an A/B test (50/50 split).
SELECT
  id AS user_id,
  CASE WHEN MOD(ABS(HASH(id)), 2) = 0 THEN 'control' ELSE 'treatment' END AS variant
FROM users;

-- "Is this minute a 5-minute boundary?"
SELECT * FROM ecom_events WHERE MOD(EXTRACT(MINUTE FROM event_timestamp), 5) = 0;

-- Wrap a counter (e.g., position 12 in a wheel of 8 → position 4).
WITH rotations(pos, wheel_size) AS (VALUES (12, 8), (20, 8))
SELECT MOD(pos, wheel_size) AS slot FROM rotations;

-- Detect divisibility (FizzBuzz-style logic).
SELECT
  n,
  CASE
    WHEN MOD(n, 15) = 0 THEN 'FizzBuzz'
    WHEN MOD(n, 3)  = 0 THEN 'Fizz'
    WHEN MOD(n, 5)  = 0 THEN 'Buzz'
    ELSE n::TEXT
  END AS label
FROM range(1, 21) AS r(n);