program.sql

-- ============================================================
-- Branchless Programming Examples in MariaDB SQL
--
-- "Branchless" means avoiding IF/CASE/WHEN conditional logic.
-- Instead, we use arithmetic expressions that always compute
-- the answer the same way, regardless of input values.
--
-- SQL-SPECIFIC NOTE:
--   In MariaDB/MySQL, boolean expressions like (a < b) evaluate
--   to 1 (true) or 0 (false) in numeric context. This is the
--   foundation of all branchless tricks in SQL:
--
--     SELECT (5 > 3);   -- Returns 1  (true)
--     SELECT (3 > 5);   -- Returns 0  (false)
--
--   We multiply by these 0/1 results to "select" values
--   without needing CASE or IF statements.
-- ============================================================

-- ----- getSign -----
-- Returns 1 for positive/zero, 0 for negative.
--
-- HOW IT WORKS:
--   (num >= 0) returns 1 when true, 0 when false.
--   That's it! No branches, just a boolean expression.
--
-- EXAMPLES:
--   getSign(42)  → (42 >= 0)  → 1  ✓
--   getSign(-7)  → (-7 >= 0)  → 0  ✓
--   getSign(0)   → (0 >= 0)   → 1  ✓
DELIMITER //
CREATE FUNCTION getSign(num INT) RETURNS INT DETERMINISTIC
BEGIN
    RETURN (num >= 0);
END//
DELIMITER ;

-- ----- minBranchless -----
-- Returns the smaller of two integers.
--
-- HOW IT WORKS:
--   (a < b) is either 1 or 0.
--   We multiply each value by its "winning condition":
--     a * (a < b)  → keeps a when a IS smaller, zeroes it out otherwise
--     b * (a >= b) → keeps b when b IS smaller or equal, zeroes it out otherwise
--   Adding them gives us the minimum.
--
-- WORKED EXAMPLE (a=15, b=9):
--   a * (a < b)  = 15 * (15 < 9) = 15 * 0 =  0
--   b * (a >= b) =  9 * (15 >= 9) = 9 * 1 =  9
--   Result: 0 + 9 = 9  ✓
--
-- WORKED EXAMPLE (a=3, b=7):
--   a * (a < b)  = 3 * (3 < 7)  = 3 * 1 = 3
--   b * (a >= b) = 7 * (3 >= 7) = 7 * 0 = 0
--   Result: 3 + 0 = 3  ✓
DELIMITER //
CREATE FUNCTION minBranchless(a INT, b INT) RETURNS INT DETERMINISTIC
BEGIN
    RETURN a * (a < b) + b * (a >= b);
END//
DELIMITER ;

-- ----- maxBranchless -----
-- Returns the larger of two integers.
--
-- Same idea as minBranchless, but we flip the conditions:
--   a * (a > b)  → keeps a when a IS larger
--   b * (a <= b) → keeps b when b IS larger or equal
--
-- WORKED EXAMPLE (a=15, b=9):
--   15 * (15 > 9) + 9 * (15 <= 9) = 15 * 1 + 9 * 0 = 15  ✓
DELIMITER //
CREATE FUNCTION maxBranchless(a INT, b INT) RETURNS INT DETERMINISTIC
BEGIN
    RETURN a * (a > b) + b * (a <= b);
END//
DELIMITER ;

-- ===== Test Queries =====

SELECT '--- Sign Tests ---' AS test_section;
SELECT 42 AS num, getSign(42) AS sign
UNION ALL SELECT -7, getSign(-7)
UNION ALL SELECT 0, getSign(0);

SELECT '--- Min/Max Tests ---' AS test_section;
SELECT 15 AS a, 9 AS b,
       minBranchless(15, 9) AS min_result,
       maxBranchless(15, 9) AS max_result;

SELECT 3 AS a, 7 AS b,
       minBranchless(3, 7) AS min_result,
       maxBranchless(3, 7) AS max_result;

-- ===== Cleanup =====
DROP FUNCTION IF EXISTS getSign;
DROP FUNCTION IF EXISTS minBranchless;
DROP FUNCTION IF EXISTS maxBranchless;