在 3 个表中使用左连接

Question

我正在尝试使用 LEFT JOIN 连接 3 个表，但我总是出错。请帮帮我。

谢谢

我想要的输出：

Name            Date              Open               Close
POS             01/01/2014         4                  10
ONE             01/02/2014         6                  5
...
...
...

我的查询：

SELECT 'Data'
||','||TO_CHAR(D.DTIME_DAY,'MM/dd/yyyy')
||','||NVL(o.CNT_OPENED,0) --as cnt_opened
||','||NVL(c.CNT_CLOSED,0) --as cnt_closed
||','||q.NAME
FROM OWNER_DWH.DC_DATE d
LEFT JOIN APP_ACCOUNT.OTRS_QUEUE q
ON t.queue_id = q.id
LEFT JOIN (
SELECT TRUNC(t.CREATE_TIME) AS report_date,count(*) AS cnt_opened
FROM APP_ACCOUNT.OTRS_TICKET t
WHERE t.CREATE_TIME BETWEEN SYSDATE -120 AND SYSDATE
GROUP BY TRUNC(t.CREATE_TIME)
) o ON d.DTIME_DAY=o.REPORT_DATE
LEFT JOIN (
SELECT TRUNC(t.CLOSE_TIME) as report_date,count(*) AS cnt_closed
FROM APP_ACCOUNT.OTRS_TICKET t
WHERE t.CLOSE_TIME BETWEEN SYSDATE -120 AND SYSDATE
GROUP BY TRUNC(t.CLOSE_TIME)
) c ON D.DTIME_DAY=c.REPORT_DATE
WHERE d.DTIME_DAY BETWEEN SYSDATE -120 AND TRUNC(SYSDATE) -1
AND d.DTIME_DAY = TRUNC(d.DTIME_DAY)
AND TRUNC(d.DTIME_DAY)= d.DTIME_DAY
ORDER BY D.DTIME_DAY;

Answer 1

您的第一个左连接中没有“t”的任何表别名。所以 oracle 在连接条件下还不知道t.queue_id 中的“t”是什么

ON t.queue_id = q.id。

来自您的代码：

SELECT 'Data'
||','||TO_CHAR(D.DTIME_DAY,'MM/dd/yyyy')
||','||NVL(o.CNT_OPENED,0) --as cnt_opened
||','||NVL(c.CNT_CLOSED,0) --as cnt_closed
||','||q.NAME
FROM OWNER_DWH.DC_DATE d
LEFT JOIN APP_ACCOUNT.OTRS_QUEUE q
ON t.queue_id = q.id
LEFT JOIN (
SELECT TRUNC(t.CREATE_TIME) AS report_date,count(*) AS cnt_opened
FROM APP_ACCOUNT.OTRS_TICKET t
WHERE t.CREATE_TIME BETWEEN SYSDATE -120 AND SYSDATE
GROUP BY TRUNC(t.CREATE_TIME)
)

别名“t”在块内定义：

LEFT JOIN ( 
SELECT TRUNC(t.CREATE_TIME) AS report_date,count(*) AS cnt_opened
FROM APP_ACCOUNT.OTRS_TICKET t
WHERE t.CREATE_TIME BETWEEN SYSDATE -120 AND SYSDATE
GROUP BY TRUNC(t.CREATE_TIME)
)

现在，由于连接 ON t.queue_id = q.id 位于此块之外（括号外），因此别名“t”此时不可用。

因此出现错误。