sql oracle group by子查询答案

【问题标题】：sql oracle group by subquerysql oracle group by子查询
【发布时间】：2018-11-14 18:00:14
【问题描述】：

我在每个日期都获得了相同的电子商务号码。我正在尝试根据日期获取电子商务价值计数，每个日期都不同，因为整个 10 月的总数只有 105，而不是 391958。知道如何按子查询的输出进行分组吗？谢谢！

SELECT   to_char(wcs1.start_tms,'DD/MM/YYYY') as dates,
(
    SELECT count(*) 
    FROM   ft_t_wcs1 wcs1,ft_t_stup stup 
    WHERE  stup.modl_id='ECOMMERC'
    AND    stup.CROSS_REF_ID=wcs1.acct_id
    AND    stup.end_tms IS NULL
) AS     ecommerce
FROM     ft_t_wcs1 wcs1, ft_t_stup stup
WHERE    wcs1.scenario='CREATE' 
AND      wcs1.acct_id IS NOT NULL 
AND      wcs1.start_tms BETWEEN add_months(TRUNC(SYSDATE,'mm'),-1) AND LAST_DAY(add_months(TRUNC(SYSDATE,'mm'),-1))
GROUP BY to_char(wcs1.start_tms,'DD/MM/YYYY')
ORDER BY to_char(wcs1.start_tms,'DD/MM/YYYY');

输出

【问题讨论】：

标签： sql oracle correlated-subquery

【解决方案1】：

尝试以下修改后的查询

select to_char(wcs1.start_tms,'DD/MM/YYYY') as dates,count(*) AS 
ecommerce
from ft_t_wcs1 wcs1, ft_t_stup stup
where stup.modl_id='ECOMMERC' and stup.CROSS_REF_ID=wcs1.acct_id and stup.end_tms is null wcs1.scenario='CREATE' and wcs1.acct_id is not null and 
wcs1.start_tms between add_months(TRUNC(SYSDATE,'mm'),-1) and 
LAST_DAY(add_months(TRUNC(SYSDATE,'mm'),-1))
group by to_char(wcs1.start_tms,'DD/MM/YYYY')
order by to_char(wcs1.start_tms,'DD/MM/YYYY');

-- 使用JOIN子句的另一种方式

select to_char(wcs1.start_tms,'DD/MM/YYYY') as dates,count(*) AS 
ecommerce
from ft_t_wcs1 wcs1 
join ft_t_stup stup
ON stup.CROSS_REF_ID=wcs1.acct_id
where stup.modl_id='ECOMMERC' and stup.end_tms is null wcs1.scenario='CREATE' and wcs1.acct_id is not null and 
wcs1.start_tms between add_months(TRUNC(SYSDATE,'mm'),-1) and 
LAST_DAY(add_months(TRUNC(SYSDATE,'mm'),-1))
group by to_char(wcs1.start_tms,'DD/MM/YYYY')
order by to_char(wcs1.start_tms,'DD/MM/YYYY');

【讨论】：

【解决方案2】：

在不了解您的表关系的情况下很难提出答案，但我可以告诉您，您的问题是您的子查询和主查询之间没有关系。您的子查询仅返回 modl_id='ECOMMERC' 的计数，因此该值将始终相同 - 在您的情况下为 105。您需要向子查询添加一个 JOIN 条件，将唯一值与您的主查询联系起来。您还需要对表名进行不同的别名，以确保您正确加入。

【讨论】：

【解决方案3】：

当您只想要一个相关的子查询时，您正在执行不必要的连接：

SELECT to_char(wcs1.start_tms,'DD/MM/YYYY') as dates,
       (SELECT count(*) 
        FROM ft_t_stup stup 
        WHERE stup.modl_id=  'ECOMMERC' AND
              stup.CROSS_REF_ID = wcs1.acct_id
              stup.end_tms IS NULL
       ) AS ecommerce
FROM ft_t_wcs1 wcs1
WHERE wcs1.scenario = 'CREATE' AND
      wcs1.acct_id IS NOT NULL AND
      wcs1.start_tms BETWEEN add_months(TRUNC(SYSDATE,'mm'),-1) AND LAST_DAY(add_months(TRUNC(SYSDATE,'mm'),-1))
GROUP BY to_char(wcs1.start_tms, 'DD/MM/YYYY')
ORDER BY to_char(wcs1.start_tms, 'DD/MM/YYYY');

【讨论】：