如果在UNION查询中未找到某些日期的记录，则返回0

Question

我有以下查询

SELECT 
    COUNT(c.ID) as RECORD_COUNT, c.WEEK_START, c.LABEL
FROM
    (SELECT 
         a.ID, TRUNC(a.START_DATE,'IW') WEEK_START, 'YES' as LABEL 
     FROM 
         TABLE1 a
     UNION ALL
     SELECT 
         b.ID, TRUNC(b.START_DATE,'IW') WEEK_START, 'NO' as LABEL 
     FROM 
         TABLE1 b
     WHERE 
         FUNCTION(b.ID) = 'Test') AS c

我得到的是每周的记录数量，出现在第一个子查询中且带有标签YES的记录数以及每周的记录数量出现在第二个子查询中且带有标签NO 。

例：

RECORD_COUNT   WEEK_START   LABEL
    100          1/28/2019  YES
     24          1/28/2019  NO
     81          2/4/2019   YES
    229          2/11/2019  YES
      6          2/11/2019  NO

很多时候，第二个子查询不返回任何记录，因此某些日期我缺少行。

在上面的示例中，对于2/4/2019的NO行未返回任何内容。

如何修改查询，使没有数据的行返回零？

我想看到的是这样的：

RECORD_COUNT   WEEK_START   LABEL
    100          1/28/2019  YES
     24          1/28/2019  NO
     81          2/4/2019   YES
      0          2/4/2019   NO
    229          2/11/2019  YES
      6          2/11/2019  NO

Answer 1

有更复杂的方法可以更普遍地工作。 但是对于您而言，这是一个简单的方法：

SELECT COUNT(c.ID) as RECORD_COUNT, c.WEEK_START, c.LABEL
FROM
(
    SELECT a.ID, 
           TRUNC(a.START_DATE,'IW') WEEK_START, 
           'YES' as LABEL 
    FROM TABLE1 a
    UNION ALL
    SELECT DECODE(FUNCTION(b.ID),'Test',b.ID,NULL) ID,
           TRUNC(b.START_DATE,'IW') WEEK_START, 
           'NO' as LABEL 
    FROM TABLE1 b
) as c

Answer 2

我建议将值放入列而不是行中：

select trunc(t.START_DATE, 'IW') as WEEK_START,
       count(*) as num_yes,
       sum(case when FUNCTION(b.ID) = 'Test' then 1 else 0 end) as num_nos
from table1
group by trunc(t.START_DATE, 'IW')
order by week_start;

如果您想要单独的行，那么我将取消透视：

with t as (
      select trunc(t.START_DATE, 'IW') as WEEK_START,
             count(*) as num_yes,
             sum(case when FUNCTION(b.ID) = 'Test' then 1 else 0 end) as num_nos
      from table1
      group by trunc(t.START_DATE, 'IW')
     )
select (case when l.label = 'YES' then t.num_yes else t.num_nos end) as record_count,
       t.week_start, l.label
from t cross join
     (select 'YES' as label from dual union all select 'NO' as label) l
order by week_start;