SQL 常用方法函数

DATEDIFF 返回两个日期之间相差几天
CONCAT 字符串拼接   
COALESCE  将空值替换成其他值   返回第一个非空值
TO_DATE 时间格式转化
DATEADD 时间加几天
SUBSTR 字符串做分割

SELECT device_id, coalesce(DATEDIFF(CONCAT(pt, " 00:00:00"), CONCAT(‘{partition}‘, ‘ 00:00:00‘), ‘dd‘), -1) as age FROM
basic_data_center.extract_ttgame_extra_app_source__userdaystat WHERE pt in (
    SUBSTR(DATEADD(TO_DATE(‘{partition}‘, ‘yyyy-mm-dd‘), 1, ‘dd‘), 1, 10),
    SUBSTR(DATEADD(TO_DATE(‘{partition}‘, ‘yyyy-mm-dd‘), 2, ‘dd‘), 1, 10),
    SUBSTR(DATEADD(TO_DATE(‘{partition}‘, ‘yyyy-mm-dd‘), 3, ‘dd‘), 1, 10),
    SUBSTR(DATEADD(TO_DATE(‘{partition}‘, ‘yyyy-mm-dd‘), 7, ‘dd‘), 1, 10),
    SUBSTR(DATEADD(TO_DATE(‘{partition}‘, ‘yyyy-mm-dd‘), 14, ‘dd‘), 1, 10),
    SUBSTR(DATEADD(TO_DATE(‘{partition}‘, ‘yyyy-mm-dd‘), 30, ‘dd‘), 1, 10)
)
and day_age != 0) as b
on a.device_id = b.device_id