오라클 오라클 PostgreSQL MSSQL Dual SELECT 1 FROM DUAL SELECT 1 SELECT 1 NULL 함수 SELECT NVL(param1, param2) DAUL NVL(param1, param2) ISNULL(param1, param2) coalesce(name, 'No Data') -- 지정 문자열 coalesce(name, null) -- null coalesce(name, '{}')::json as name -- json coalesce(name, id) -- 컬럼 DECODE DECODE CASE WHEN THEN ELSE END IIF( boolean_expression, true_value, false_value ) ..