[英]Oracle left outer join issue
我在使用左外部聯接的報表SQL中遇到問題。
SELECT * FROM xx.aa
LEFT OUTER JOIN xx.yyy
ON aa.some_column_1 = yyy.some_column_1
AND aa.some_column_2 = yyy.some_column_2
AND aa.some_column_3 = yyy.some_column_3
AND yyy.some_year = '2015'
AND yyy.some_column_4 IS NOT NULL
AND yyy.some_column_4 > 0
WHERE aa.some_column_1 = '1234'
AND aa.some_column_2 = 'SOME_VALUE'
AND aa.end_date >= TO_DATE('01-JAN-2015','DD-MON-YYYY')
AND aa.start_date <= TO_DATE('31-DEC-2015','DD-MON-YYYY')
AND (aa.some_column_3 = 'SOME_VALUE')
表aa
some_column_1 some_column_2 some_column_3 start_date end_date
1234 SOME_VALUE SOME_VALUE 1/1/2011 6/30/2014
1234 SOME_VALUE SOME_VALUE 7/1/2014 6/30/2015
表yyy
some_column_1 some_column_2 some_column_3 some_column_4 some_year
1234 SOME_VALUE SOME_VALUE 444 2015
但是,僅當存在多於1行匹配且行中至少有一個滿足兩個條件時,才應應用左外部連接的最后兩個條件IS NOT NULL
和> 0
。 否則將是一個問題。
有任何想法嗎?
您應該在左聯接中不帶條件的情況下運行查詢,然后對條件進行判斷,以從yyy表中確定值是否為空。
select aa_col1, aa_col2, ..., aa_coln,
case when cnt > 2 and cond > 1
and not (yyy_some_column_4 IS NOT NULL AND yyy_some_column_4 > 0)
then null else yyy_col1
end as yyy_col1,
,...the other columns of yyy
from(
SELECT aa.*, yyy.*,
count(*) over() as cnt,
count(case when yyy.some_column_4 IS NOT NULL AND yyy.some_column_4 > 0 then 1 end) over() as cond
FROM xx.aa
LEFT OUTER JOIN xx.yyy
ON aa.some_column_1 = yyy.some_column_1
AND aa.some_column_2 = yyy.some_column_2
AND aa.some_column_3 = yyy.some_column_3
AND yyy.some_year = '2015'
WHERE aa.some_column_1 = '1234'
AND aa.some_column_2 = 'SOME_VALUE'
AND aa.end_date >= TO_DATE('01-JAN-2015','DD-MON-YYYY')
AND aa.start_date <= TO_DATE('31-DEC-2015','DD-MON-YYYY')
AND (aa.some_column_3 = 'SOME_VALUE')
)
在第8行,您應該對列進行別名處理,以便它們在上方的選擇中區分開。 我將它們命名為aa_col1,yyy_col1等。
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