Oracle LISTAGG案例返回不同的值

Question

我正在用LISTAGG編寫ORACLE select語句。 它可以工作，但是當我驗證數據時，我看到了1：1,1：1,2：2,2：2之類的重復項。

我驗證數據庫確實有重復項。 查詢是一對一關系中的兩個表。 以下是我的查詢的摘要，但我更改了列名等。

如何修改以下查詢以返回每個人的唯一值？

謝謝

SELECT Table1.PERSON_ID, 
       Table1.FIRST_NAME,
       Table1.MIDDLE_NAME,
       Table1.LAST_NAME,

LISTAGG(case  
        when Table2.DESCRIPTION = '1' then '1:1'
        when Table2.DESCRIPTION = '2' then '2:2'
        when Table2.DESCRIPTION = '3' then '3:3'
        when Table2.DESCRIPTION = '4' then '4:4'
        when Table2.DESCRIPTION = '5' then '5:5'
        when Table2.DESCRIPTION = '6' then '6:6'
        when Table2.DESCRIPTION = '7' then '7:7'
        when Table2.DESCRIPTION = '8' then '8:8'
        when Table2.DESCRIPTION = '9' then '9:9'


      else ''

 end, ',')  
WITHIN GROUP (ORDER BY Table2.DESCRIPTION )  

FROM Table1
LEFT JOIN Table2

ON Table2.PERSON_ID = Table1.PERSON_ID
GROUP BY Table1.PERSON_ID,Table1.FIRST_NAME,Table1.MIDDLE_NAME, Table1.LAST_NAME

Answer 1

在Oracle中，您需要在子查詢中執行DISTINCT ：

SELECT PERSON_ID, FIRST_NAME, MIDDLE_NAME, LAST_NAME,
        LISTAGG(val, ',') WITHIN GROUP (ORDER BY DESCRIPTION )
FROM (SELECT DISTINCT Table1.PERSON_ID, Table1.FIRST_NAME, Table1.MIDDLE_NAME, Table1.LAST_NAME, Table2.Description
             (case when Table2.DESCRIPTION = '1' then '1:1'
                   when Table2.DESCRIPTION = '2' then '2:2'
                   when Table2.DESCRIPTION = '3' then '3:3'
                   when Table2.DESCRIPTION = '4' then '4:4'
                   when Table2.DESCRIPTION = '5' then '5:5'
                   when Table2.DESCRIPTION = '6' then '6:6'
                   when Table2.DESCRIPTION = '7' then '7:7'
                   when Table2.DESCRIPTION = '8' then '8:8'
                   when Table2.DESCRIPTION = '9' then '9:9'
                   else ''
              end) as val
      FROM Table1 LEFT JOIN
           Table2
           ON Table2.PERSON_ID = Table1.PERSON_ID
     ) 
GROUP BY PERSON_ID, FIRST_NAME, MIDDLE_NAME, LAST_NAME;

Answer 2

假設Table2將PERSON_ID作為指向Table1外鍵，則需要替換

FROM Table1
LEFT JOIN Table2
ON Table2.PERSON_ID = Table1.PERSON_ID

與

FROM Table1
LEFT JOIN 
(SELECT DISTINCT PERSON_ID, DESCRIPTION FROM Table2) T2
ON T2.PERSON_ID = Table1.PERSON_ID

然后在LISTAGG()中將Table2更改為T2 （包括WITHIN GROUP (ORDER BY ...)子句！）