Question

我需要过去24小时内每小时的记录数量，如果当天任何特定小时内没有记录，我需要显示0，我只能获得数小时的数据在表格中。

SELECT TRUNC(systemdate,'HH24') + (trunc(to_char(systemdate,'mi')/10)*10)/24/60 AS date1, 
 count(*) AS txncount
FROM transactionlog 
GROUP BY TRUNC(systemdate,'HH24') + (trunc(to_char(systemdate,'mi')/10)*10)/24/60 order by date1 desc;

结果：

如何获取过去24小时内每小时的数据？

预期数据：

记录最近24小时内每小时的计数，从当前日期开始。如果该特定小时内没有记录，则显示0。

Answer 1

你可以用这个：

WITH transactionlog AS 
(
    SELECT TO_DATE('03/05/2018 01:12','dd/mm/yyyy hh24:mi') AS systemdate, 60 AS value 
    FROM dual UNION ALL 
    SELECT TO_DATE('03/05/2018 01:32','dd/mm/yyyy hh24:mi'), 35 FROM dual UNION ALL 
    SELECT TO_DATE('03/05/2018 09:44','dd/mm/yyyy hh24:mi'), 31 FROM dual UNION ALL 
    SELECT TO_DATE('03/05/2018 08:56','dd/mm/yyyy hh24:mi'), 24 FROM dual UNION ALL 
    SELECT TO_DATE('03/05/2018 08:02','dd/mm/yyyy hh24:mi'), 98 FROM dual 
)
, time_range AS 
(
    SELECT TRUNC(sysdate, 'hh24') - 23/24 + (ROWNUM - 1) / 24 AS time1
    FROM all_objects
    WHERE ROWNUM <= 24
)
SELECT TO_CHAR(r.time1, 'mm/dd/yyyy hh:mi AM') AS date1,
    COUNT(t.systemdate) AS txncount
FROM time_range r
LEFT JOIN transactionlog t
ON r.time1 = TRUNC(t.systemdate, 'hh24') --+ 1/24
GROUP BY r.time1
ORDER BY r.time1;

如果01:12 AM表示结果中的02:00 AM，则省略注释码。

参考：Generating Dates between two date ranges_AskTOM

编辑：对于OP，你只需要这个：

WITH time_range AS 
(
    SELECT TRUNC(sysdate, 'hh24') - 23/24 + (ROWNUM - 1) / 24 AS time1
    FROM all_objects
    WHERE ROWNUM <= 24
)
SELECT TO_CHAR(r.time1, 'mm/dd/yyyy hh:mi AM') AS date1,
    COUNT(t.systemdate) AS txncount
FROM time_range r
LEFT JOIN transactionlog t
ON r.time1 = TRUNC(t.systemdate, 'hh24') --+ 1/24
GROUP BY r.time1
ORDER BY r.time1;

Answer 2

以下可能是您所需要的。当我针对all_objects视图运行它时似乎有效。

WITH date_range
  AS (SELECT TRUNC(sysdate - (rownum/24),'HH24') as the_hour
        FROM dual
      CONNECT BY ROWNUM <= 1000),
     the_data
  AS (SELECT TRUNC(created, 'HH24')  as cr_ddl, count(*) as num_obj
        FROM all_objects
      GROUP BY TRUNC(created, 'HH24'))   
SELECT TO_CHAR(dr.the_hour,'DD/MM/YYYY HH:MI AM'), NVL(num_obj,0)
FROM date_range dr LEFT OUTER JOIN the_data  ao
     ON ao.cr_ddl =  dr.the_hour
ORDER BY dr.the_hour DESC

'date_range'生成过去24小时内每小时的记录 'the_data'根据截断到小时的日期计算目标表中的记录数。
主查询然后外部加入其中两个显示子查询中的日期和计数我更喜欢在他们自己的CTE中查询的两个部分，因为它使得实际查询非常明显并且“干净”。

就您的查询而言，您需要这个;

WITH date_range
  AS (SELECT TRUNC(sysdate - (rownum/24),'HH24') as the_hour
        FROM dual
      CONNECT BY ROWNUM <= 24),
     the_data
  AS (SELECT TRUNC(systemdate, 'HH24')  as log_date, count(*) as num_obj
        FROM transactionlog 
      GROUP BY TRUNC(systemdate, 'HH24'))   
SELECT TO_CHAR(dr.the_hour,'DD/MM/YYYY HH:MI AM'), NVL(trans_log.num_obj,0)
FROM date_range dr LEFT OUTER JOIN the_data  trans_log
     ON trans_log.log_date =  dr.the_hour
ORDER BY dr.the_hour DESC

Answer 3

您需要按原始表格编写最近24小时日历表，然后LEFT JOIN 日历表。

count(t.systemdate)需要计算t.systemdate，因为t.systemdate可能是NULL
connect by创建最近24小时的日历表
on子句TO_CHAR(t.systemdate,'YYYY/MM/DD hh24','nls_language=american')确保dateformat语言相同。

你可以试试这个。

WITH Hours as 
(
  select sysdate + (level/24) dates
  from dual 
  connect by level <= 24
)
SELECT TO_CHAR(h.dates,'YYYY-MM-DD HH24') AS dateHour, count(t.systemdate) AS totlecount
FROM Hours h
LEFT JOIN transactionlog t
on TO_CHAR(t.systemdate,'YYYY/MM/DD hh24','nls_language=american') 
    = TO_CHAR(h.dates,'YYYY/MM/DD hh24','nls_language=american')
GROUP BY h.dates
ORDER BY h.dates

sqlfiddle：http://sqlfiddle.com/#!4/73db7/2

CTE递归版本

您还可以使用 CTE Recursive 来编写日历表

WITH Hours(dates,i) as 
(
   SELECT sysdate,1 
   FROM DUAL
   UNION ALL 
   SELECT sysdate + (i/24),i+1
   FROM Hours
   WHERE i<24
)
SELECT TO_CHAR(h.dates,'YYYY-MM-DD HH24') AS dateHour, count(t.systemdate) AS totlecount
FROM Hours h
LEFT JOIN transactionlog t
on TO_CHAR(t.systemdate,'YYYY/MM/DD hh24','nls_language=american') 
    = TO_CHAR(h.dates,'YYYY/MM/DD hh24','nls_language=american')
GROUP BY h.dates
ORDER BY h.dates

sqlfiddle：http://sqlfiddle.com/#!4/73db7/7

获取过去24小时内每小时的记录数

3 个答案: