using if and or statement in sql query code example

Example 1: if in sql

-- PL/SQL
BEGIN
    IF my_val = 1 THEN [...]
    ELSE [...]
    END IF;
END;
-- In a query (DUAL is for Oracle)
SELECT CASE WHEN my_col = 1 THEN 'Ok' ELSE 'Ko' END AS my_result
FROM DUAL;

Example 2: if in sql

SELECT 
  IF(500<1000, "YES", "NO");