1. IFNULL()

SAMPLE.column 값이 NULL이면 0으로 대체하여 반환

SELECT IFNULL(column, 0) AS column
FROM SAMPLE;

2. IF()

SAMPLE.column 값이 NULL이면 0, 아니면 1 반환

SELECT IF(column IS NULL, 0, 1) AS column
FROM SAMPLE;

3. CASE

SAMPLE.column 값이 NULL이면 0, 아니면 1 반환

SELECT 
	CASE
    	WHEN column IS NULL THEN 0
        ELSE 1
   	END AS column
FROM SAMPLE;