相関サブクエリを削除する方法

Question

相関サブクエリを使用しないようにこのクエリを書き直したいが、クエリから同じ出力を達成する。

SELECT 
TABLE_1.REC_ID, 
TO_CHAR(table_1.REPORT_DATE, 'DD-MON-YY HH:MI:SS') report_date, 
(
    SELECT 
    MAX(table_3.NOTE_DATE) AS MAX_DATE 
    FROM 
    table_3 
    WHERE 
    table_3.REC_ID  = table_1.REC_ID 
    AND table_3.NOTE_DATE <= table_1.REPORT_DATE 
) 
notes_max_date 
FROM 
table_1 
ORDER BY 
To_date(table_1.REPORT_DATE, 'DD-MON-YY HH:MI:SS') 

そして、次のように出力は次のようになります。次のように

CREATE TABLE "TABLE_1" 
( "SITE_ID" NUMBER(*,0), 
"USER_ID" NUMBER(*,0), 
"REC_ID" NUMBER, 
"REPORT_DATE" DATE 
) ; 

CREATE TABLE "TABLE_2" 
( "SITE_ID" NUMBER, 
"NOTE_DATE" DATE, 
"NOTES" VARCHAR2(2000 BYTE), 
"USER_ID" NUMBER, 
"REC_ID" NUMBER 
) ; 

CREATE TABLE "TABLE_3" 
( "SITE_ID" NUMBER, 
"NOTE_DATE" DATE, 
"HELP_NOTES" VARCHAR2(2000 BYTE), 
"USER_ID" NUMBER, 
"REC_ID" NUMBER 
) ; 

REM INSERTING into TABLE_1 
Insert into TABLE_1 (SITE_ID,USER_ID,REC_ID,REPORT_DATE) values (1,6165,121,to_date('17-APR-10','DD-MON-RR')); 
Insert into TABLE_1 (SITE_ID,USER_ID,REC_ID,REPORT_DATE) values (1,6165,121,to_date('01-MAY-10','DD-MON-RR')); 
Insert into TABLE_1 (SITE_ID,USER_ID,REC_ID,REPORT_DATE) values (1,6165,121,to_date('08-MAY-10','DD-MON-RR')); 
Insert into TABLE_1 (SITE_ID,USER_ID,REC_ID,REPORT_DATE) values (1,6165,121,to_date('24-APR-10','DD-MON-RR')); 
Insert into TABLE_1 (SITE_ID,USER_ID,REC_ID,REPORT_DATE) values (1,6165,121,to_date('15-MAY-10','DD-MON-RR')); 
Insert into TABLE_1 (SITE_ID,USER_ID,REC_ID,REPORT_DATE) values (1,6165,121,to_date('05-JUN-10','DD-MON-RR')); 
Insert into TABLE_1 (SITE_ID,USER_ID,REC_ID,REPORT_DATE) values (1,6165,121,to_date('22-MAY-10','DD-MON-RR')); 
Insert into TABLE_1 (SITE_ID,USER_ID,REC_ID,REPORT_DATE) values (1,6165,121,to_date('29-MAY-10','DD-MON-RR')); 

REM INSERTING into TABLE_2 
Insert into TABLE_2 (SITE_ID,NOTE_DATE,NOTES,USER_ID,REC_ID) values (1,to_date('13-APR-10','DD-MON-RR'),'Notes - we need stuff.',6165,121); 

REM INSERTING into TABLE_3 
Insert into TABLE_3 (SITE_ID,NOTE_DATE,HELP_NOTES,USER_ID,REC_ID) values (1,to_date('17-MAY-10','DD-MON-RR'),'Entry #1',1932,121); 
Insert into TABLE_3 (SITE_ID,NOTE_DATE,HELP_NOTES,USER_ID,REC_ID) values (1,to_date('12-MAY-10','DD-MON-RR'),'Entry #2',6005,121); 
Insert into TABLE_3 (SITE_ID,NOTE_DATE,HELP_NOTES,USER_ID,REC_ID) values (1,to_date('25-MAY-10','DD-MON-RR'),'Entry #3',1932,121); 

ALTER TABLE "TABLE_1" MODIFY ("REC_ID" NOT NULL ENABLE); 
-------------------------------------------------------- 
-- Constraints for Table TABLE_2 
-------------------------------------------------------- 

    ALTER TABLE "TABLE_2" MODIFY ("SITE_ID" NOT NULL ENABLE); 

    ALTER TABLE "TABLE_2" MODIFY ("REC_ID" NOT NULL ENABLE); 
-------------------------------------------------------- 
-- Constraints for Table TABLE_3 
-------------------------------------------------------- 

    ALTER TABLE "TABLE_3" MODIFY ("SITE_ID" NOT NULL ENABLE); 

    ALTER TABLE "TABLE_3" MODIFY ("REC_ID" NOT NULL ENABLE); 

クエリがある

REC_ID     REPORT_DATE  NOTES_MAX_DATE    
---------------------- ------------------ ------------------------- 
121     17-APR-10 12:30:00       
121     24-APR-10 12:30:00       
121     01-MAY-10 12:30:00       
121     08-MAY-10 12:30:00       
121     15-MAY-10 12:30:00 12-MAY-10     
121     22-MAY-10 12:30:01 17-MAY-10     
121     29-MAY-10 12:30:01 25-MAY-10     
121     05-JUN-10 12:30:00 25-MAY-10     
8 rows selected 

出力は8行可能とNOTES_MAX_DATE colummでNULLを含める必要があります。ありがとう！

Answer 1

あなたはこのようなLEFT JOINとGROUP BYでそれを書き換えることができます：

SELECT t1.REC_ID 
     ,to_char(t1.REPORT_DATE, 'DD-MON-YY HH:MI:SS') AS report_date 
     ,max(t3.NOTE_DATE) AS notes_max_date 
FROM table_1 AS t1 
LEFT JOIN table_3 AS t3 ON t3.REC_ID = t1.REC_ID 
         AND t3.NOTE_DATE <= t1.REPORT_DATE 
GROUP BY t1.REC_ID 
     ,to_char(t1.REPORT_DATE, 'DD-MON-YY HH:MI:SS') 
ORDER BY to_date(t1.REPORT_DATE, 'DD-MON-YY HH:MI:SS')