[MySQL] 실습 내용 [STRING, ORDER BY, DATE, TYPE CASTING]

기본 문법 1) STRING

SELECT
	LENGTH(channel),
    UPPER(channel),
    LOWER(channel),
    LEFT(channel, 4),
    RPAD(channel, 15, '-')
FROM prod.channel;

기본 문법 2) ORDER BY

SELECT value
FROM prod.count_test
ORDER BY value DESC;

 

기본 문법 3) ORDER BY 2 (위와 같은 결과)

SELECT value
FROM prod.count_test
ORDER BY 1 DESC;

 

기본 문법 4) ORDER BY 3

SELECT value
FROM prod.count_test
ORDER BY value ASC;

 

기본 문법 5) DATE 관련 함수들 1

SELECT
	created, CONVERT_TZ(created, 'GMT', 'Asia/Seoul') seoul_time,
    YEAR(created) y, QUARTER(created) q, MONTH(created) m, MOINTHNAME(created) mnn,
    DATE(created) d, HOUR(created) h, MINUE(created) m, SECOND(created) s
FROM session
LIMIT 10;

 

기본 문법 6) DATE 관련 함수들 2

SELECT
	DATEDIFF(now(), created) gap_in_days,
    DATE_ADD(created, INTERVAL 10 DAY) ten_datys_after_created
FROM session
LIMIT 10;

 

기본 문법 7) DATE 관련 함수들 3

SELECT STR_TI_DATE('01,5,2013','%d,%m,%Y');

 

기본 문법 8) TYPE CASTING

SELECT cast('100.0' as float), convert('100.0', float);