一、随机示例（想到哪里写哪里）

1.系统时间函数

查询

select current_timestamp --当前格式化时间,current_date      --当前格式化日期,unix_timestamp()  --当前unix时间戳

结果：

2.时间函数转换

查询

--将时间戳转化为格式化时间
select from_unixtime(1725865044),from_unixtime(1725865044,'yyyy-MM-dd'),from_unixtime(1725865044,'yyyy-MM'),from_unixtime(1725865044,'dd')

结果

查询

--时间格式化为日期
select to_date('2024-09-09 14:57:24')

 结果

查询

--日期格式化
select date_format('2024-09-09 14:57:24','yyyy-MM-dd'),date_format('2024-09-09','yyyy-MM'),date_format('2024-09-09','yyyy')

 结果

3.时间函数

查询

select current_date              as curr_day      --当日,year(current_date)        as curr_year     --年,quarter(current_date)     as curr_quarter  --季度,weekofyear(current_date)  as curr_week     --年周,month(current_date)       as curr_month    --月,day(current_date)         as curr_day1     --日,hour(current_timestamp)   as curr_hour     --时,minute(current_timestamp) as curr_minute   --分,second(current_timestamp) as curr_second   --秒

 结果

4.计算类函数

查询

select current_date,date_sub(current_date,1)            as yesterday,date_add(current_date,1)            as nextday,datediff('2024-09-11','2024-09-10') as diff_days,add_months(current_date,-1)         as lastmonth_day,add_months(current_date,1)          as nextmonth_day,next_day(current_date,'Mon')        as nextmonday,last_day(current_date)              as lastday

结果

5.常用日期

查询

--统计周期内第一天
select current_date                              as curr_day      --当日,trunc(current_date,'YY')                  as curr_year     --当年第一天,trunc(current_date,'Q')                   as curr_quarter  --当季度第一天,trunc(current_date,'MM')                  as curr_month    --当月第一天,date_sub(next_day(current_date, 'MO'), 7) as curr_week     --当周第一天

结果