[MySQL] IF / CASE 문

1. IF문

IF (조건문, 참일 때 값, 거짓일 때 값) 

EX. 

SELECT IF(FREEZE_YR IS NULL, "N", FREEZE_YR) AS FREEZE_YR
FROM TABLE 

SELECT IF(column1 <= 3, "Small", "Big) AS Result 
FROM TABLE 

2. CASE WHEN문

CASE
	WHEN 조건 1 THEM '결과값1' 
    WHEN 조건 2 THEN '결과값2' 
    ELSE '나머지 결과값 3' 
END 

Ex. 

SELECT CASE
	WHEN (FREEZE_YR IS NULL) THEN 'N" 
    WHEN (FREEZE_YR BETWWEN 1 AND 1999) THEN "Old" 
    ELSE "NEW" 
END AS RESULT 
FROM TABLE 

IF NULL 조건문

IFNULL(값1, 대체값)

EX. 

SELECT IFNULL(FREEZE_YR, 'N") 
FROM TABLE