oracle 左連接四表關聯查詢示例

 

1.情景展示

　　查詢指定時間段內的某卡的每天的注冊量

2.原因分析

　　使用group by按天進行分組查詢，並將查詢結果看做一張表；

　　connect by遞歸查詢出指定時間段所橫跨的日期作為主表，注冊量作為輔表，與主表日期進行關聯查詢 

3.解決方案

SELECT NVL(APP_ZS, 0) ONLINE_FORMAL, --''轉0
       NVL(APP_LS, 0) ONLINE_INFORMAL,
       NVL(JG_ZS, 0) OFFLINE_FORMAL,
       NVL(JG_LS, 0) OFFLINE_INFORMAL,
       D.REGDATE REGTIME
  FROM (SELECT COUNT(1) APP_ZS, /*線上正式卡注冊量*/
               TO_CHAR(V.REGTIME, 'YYYY-MM-DD') REGDATE
          FROM VIRTUAL_CARD V, APP_ACCESS A
         WHERE V.IDENTIFIER = A.ID
         GROUP BY TO_CHAR(V.REGTIME, 'YYYY-MM-DD')) ONLINE_FORMAL_CARD_REGIST,
       (SELECT COUNT(1) APP_LS, /*線上臨時卡注冊量*/
               TO_CHAR(V.REGTIME, 'YYYY-MM-DD') REGDATE
          FROM VIRTUAL_CARD_INTERIM V, APP_ACCESS A
         WHERE V.IDENTIFIER = A.ID
         GROUP BY TO_CHAR(V.REGTIME, 'YYYY-MM-DD')) ONLINE_INFORMAL_CARD_REGIST,
       (SELECT COUNT(1) JG_ZS, /*線下正式卡注冊量*/
               TO_CHAR(V.REGTIME, 'YYYY-MM-DD') REGDATE
          FROM VIRTUAL_CARD V, ORG_ACCESS O
         WHERE V.IDENTIFIER = O.ID
         GROUP BY TO_CHAR(V.REGTIME, 'YYYY-MM-DD')) OFFLINE_FORMAL_CARD_REGIST,
       (SELECT COUNT(1) JG_LS, /*線下臨時卡注冊量*/
               TO_CHAR(V.REGTIME, 'YYYY-MM-DD') REGDATE
          FROM VIRTUAL_CARD_INTERIM V, ORG_ACCESS O
         WHERE V.IDENTIFIER = O.ID
         GROUP BY TO_CHAR(V.REGTIME, 'YYYY-MM-DD')) OFFLINE_INFORMAL_CARD_REGIST,
       /*左連接（以天為主表）*/
       (SELECT TO_CHAR(TO_DATE('2020-06-01', 'YYYY-MM-DD') + ROWNUM - 1,
                       'YYYY-MM-DD') AS REGDATE
          FROM DUAL
        CONNECT BY ROWNUM <=
                   TRUNC(TO_DATE('2020-06-17', 'YYYY-MM-DD') -
                         TO_DATE('2020-06-01', 'YYYY-MM-DD')) + 1) D
 WHERE D.REGDATE = ONLINE_FORMAL_CARD_REGIST.REGDATE(+)
   AND D.REGDATE = ONLINE_INFORMAL_CARD_REGIST.REGDATE(+)
   AND D.REGDATE = OFFLINE_FORMAL_CARD_REGIST.REGDATE(+)
   AND D.REGDATE = OFFLINE_INFORMAL_CARD_REGIST.REGDATE(+)
 ORDER BY D.REGDATE;

 

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