Greenplum日期函数记录

工作中经常用到greenplum日期函数,特此记录,以便查阅!
  1. 查询时间戳对应的年月日时分秒
    select extract(century from timestamp '2018-08-01 12:12:13'); > 21 select extract(year from timestamp '2018-08-01 12:12:13'); > 2018 select extract(month from timestamp '2018-08-01 12:12:13'); > 8 select extract(day from timestamp '2018-08-01 12:12:13'); > 1 select extract(hour from timestamp '2018-08-01 12:12:13'); > 12 select extract(min from timestamp '2018-08-01 12:12:13'); > 12 select extract(sec from timestamp '2018-08-01 12:12:13'); > 13

  2. 查询日期之间的天数差,date_depart参数为day时,返回两个日期之间的天数差,month 不起作用,hour则只截取两个日期的hour做差,不能用;月份差可在天数差的基础上除以30,算作基础的月份差。
    select date_part('day','2022-05-01 00:00:00'::timestamp - '2021-03-01 00:00:00'::timestamp) > 61 select date_part('month','2022-05-01 12:00:00'::timestamp - '2021-03-01 00:00:00'::timestamp) > 0 select date_part('hour','2022-05-01 12:00:00'::timestamp - '2021-03-01 00:00:00'::timestamp) > 12 select date_part('day','2022-05-01 00:00:00'::timestamp - '2021-03-01 00:00:00'::timestamp)/30 > 2

  3. 查询分组的字符串拼接函数
    string_agg(A,B),需配合分组使用,A是拼接字段,B是分隔符号以及字符串拼接的排序,与mysql中的group_contact()是一个作用。例如,返回订单表中不同用户的累计信息渠道,一个用户可能在一个信息渠道停留多次,需要去重,不同的信息渠道进行拼接,且针对所有用户拼接字段的顺序要相同一致:
    selectsuperid , string_agg(tag_value,',' order by tag_value) as tag_value from ( select superid,tag_value from ( select b.superid, (case when trim(a.order_channel)='CMS' then '可控门店' when trim(a.order_channel)='EOS' then '焕新服务' when trim(a.order_channel)='E3' then order_source else '微商城' end )as tag_value from cdp_order_model a join superid_all b on a.customer_id = b.id and b.idtype ='jiami_mobile' where channel='cdp_order_sale_01' ) c group by c.superid,c.tag_value )a group by superid > 11111可控门店,焕新服务 2222可控门店,焕新服务 3333可控门店

  4. 获取当前时间
    select now() > 2022-05-20 18:47:17.706284+08 select current_date > 2022-05-20 select current_timestamp > 2022-05-20 18:47:17.706284+08

  5. 【Greenplum日期函数记录】将日期转换为字符串
    select cast(date_column as varchar)

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