每个用户的选择行与当天的最新时间

我能够从我需要的数据库中获取数据，除了我只需要每个日期的一行，所以例如在下面的图片应该只有第二行不是第一个。我不知何故需要能够从一个日期为一个用户获得一行。每个用户的选择行与当天的最新时间

SELECT id_user, date_created || ' ' || time_created as placed 
      FROM (
         SELECT 
         b_objednavky.uzivatel AS id_uzivatele, 
         b_objednavky.vytvoreno::date AS date_created, 
         to_char(b_objednavky.vytvoreno, 'HH24:MI:SS') as time_created, 
         b_objednavky.created 

        FROM b_objednavky 
        INNER JOIN u_uzivatele ON b_objednavky.uzivatel = (
        SELECT u_uzivatele.id from u_uzivatele JOIN bw_paid_orders 
          ON u_uzivatele.id = bw_paid_orders.user_id 
        WHERE bw_paid_orders.active_thru < NOW() + interval '6 months' 
        ) uzivatele 
        INNER JOIN bc_stavy_objednavky ON b_objednavky.stav = bc_stavy_objednavky.id 

        WHERE bc_stavy_objednavky.sysid = 'nova' AND b_objednavky.vytvoreno <= NOW() 
        AND bc_staty.kod NOT IN (
         'BR', 'CL', 'AR', 'MX' 
        ) 

       ) AS order 
       LEFT OUTER JOIN (
        SELECT user_id, max(paid) as last_paid FROM bw_paid_orders 
       GROUP BY user_id 
       ) last_paid_by_user ON (id_user = user_id) 
       WHERE (created > last_paid OR last_paid IS NULL) AND created BETWEEN ('2017-02' || '-01')::date 
      AND ('2017-02' || '-01')::DATE + '1 month'::interval 
      ORDER BY datum_objednani DESC, objednavajici, nazev, duration

来源

2017-02-22 jemcaj

放入CTE使用ROW_NUMBER在（分区通过任何参考u的使用），并从该CTE其中ROWNUMBER = 1 –

使用DISTINCT ON

得到的只是一排为一个用户从一个日期

SELECT DISTINCT ON (id_user, date_created) ...

要获得最新的该行的时间为一天，加上（在相同的查询级别）：

ORDER BY id_user, date_created, time_created DESC NULLS LAST

详情：

Select first row in each GROUP BY group?

来源

2017-02-22 15:54:37

而且我应该在哪里使用它选择？在哪个条款中？我有点迷失在那 – jemcaj

@jemcaj：在开始的'select'右边，就像Erwin显示 –

@jemcaj：你是否按照链接？ –

每个用户的选择行与当天的最新时间

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