基于两个数据库表之间的数据比较创建oracle视图

如何解决基于两个数据库表之间的数据比较创建oracle视图

我有下表：

• 我要创建一个视图，以便对于两个表中的descr = 'O'和公共id_isin字段值，检查ratio字段并仅占据ratio字段所在的行值低。
• 对于descr = 'O'，如果id_isin存在于一个表中但不存在于另一个表中，则取这些行（双向）
• 对于descr ! = 'O'中的所有行，从表IS_ID_TST中获取所有这些行。

下面是视图的预期输出，例如：

ID_ISIN   QUOTE_CRNY   DESCR           RATIO              ALLOCATIONASSETTYPE
L000123    USD              O              0.0769          Other total
L000129    USD              O              0.0669          Other total
D123458    USD              O              0.64039         Other total
M123456    USD              O              5.64039         Other total
F563458    USD              C              0.84039         Other total
G123456    USD              null           0.04039         Other total
L000123    USD              C              5.0769          Other total

我可以根据此条件创建视图吗？

解决方法

您需要LEAST()函数以及3个与UNION子句结合的子查询。表中的两个子查询应包含FULL JOIN：

CREATE VIEW V_MEMBER_FUND AS    
SELECT i.fund_isin,i.member_descr,LEAST(i.member_ratio,t.member_ratio) AS member_ratio,i.allocationassettype
  FROM IS_ID i
  JOIN IS_ID_TST t
    ON t.fund_isin = i.fund_isin
   AND t.member_descr = i.member_descr
 WHERE i.member_descr = 'O'
UNION
SELECT LEAST(NVL(i.fund_isin,t.fund_isin),NVL(t.fund_isin,i.fund_isin)) AS fund_isin,LEAST(NVL(i.member_descr,t.member_descr),NVL(t.member_descr,i.member_descr)) AS member_descr,LEAST(NVL(i.member_ratio,t.member_ratio),NVL(t.member_ratio,i.member_ratio)) AS member_ratio,LEAST(NVL(i.allocationassettype,t.allocationassettype),NVL(t.allocationassettype,i.allocationassettype)) AS allocationassettype
  FROM IS_ID i
  FULL JOIN IS_ID_TST t
    ON t.fund_isin = i.fund_isin
 WHERE (i.member_descr = 'O' OR t.member_descr = 'O' )
   AND ( t.fund_isin IS NULL OR i.fund_isin IS NULL )
UNION
SELECT t.fund_isin,t.member_descr,t.member_ratio,t.allocationassettype
  FROM IS_ID i
 RIGHT JOIN IS_ID_TST t
    ON t.fund_isin = i.fund_isin
   AND t.member_descr = i.member_descr
 WHERE (NVL(i.member_descr,'XYZ') != 'O' OR NVL(t.member_descr,'XYZ') != 'O' )
   AND t.fund_isin IS NOT NULL  

在 first 情况下：只需要返回具有i.member_descr = 'O'个匹配项的member_ratio的最小值。

在第二情况下：告知需要双向（FULL JOIN）逻辑

对于第三种情况：需要一个{strong>外部联接分别对应于IS_ID_TST表的位置（在当前情况下为RIGHT JOIN）连同member_desct到值'O'的非等价值（甚至应消除NULL值，并为此目的添加NVL()函数）>

在这三种情况下指定的所有子查询都应与UNION组合，以提供逐行组合，包括消除重复的行。

Demo

,

我想出了以下查询，请检查我是否对查询发表了评论。询问是否不符合您的要求或进行任何澄清。

CREATE VIEW v_combined_data AS
WITH combined_data
AS
(
SELECT t1.fund_isin,t1.fund_quote_crny,t1.member_descr,t1.member_ratio,t1.allocationassettype,t2.fund_isin fund_isin_tst,t2.fund_quote_crny fund_quote_crny_tst,t2.member_descr member_descr_tst,t2.member_ratio member_ratio_tst,t2.allocationassettype allocationassettype_tst
FROM   is_id t1
FULL   OUTER JOIN is_id_tst t2
ON     t1.fund_isin = t2.fund_isin
AND    t1.fund_quote_crny = t2.fund_quote_crny
AND    t1.member_descr = t2.member_descr
)
-- for member_descr = 'O' and for common fund_isin field value from both tables,-- check the member_ratio field and take only the row where member_ratio field value is low.
SELECT d.fund_isin,d.fund_quote_crny,d.member_descr,LEAST(d.member_ratio,d.member_ratio_tst) member_ratio,d.allocationassettype
  FROM combined_data d
WHERE d.member_descr = 'O'
  AND d.fund_isin IS NOT NULL 
  AND d.fund_isin_tst IS NOT NULL
UNION ALL
--for member_descr = 'O' and if the fund_isin exist in one table but not in another then take those rows(bidirectional)
--exists in IS_ID and not in IS_ID_TST
SELECT d.fund_isin,d.member_ratio,d.allocationassettype
  FROM combined_data d
WHERE d.member_descr = 'O'
  AND NOT EXISTS (SELECT 1
                    FROM combined_data ci
                   WHERE ci.fund_isin_tst = d.fund_isin
                     AND ci.fund_quote_crny_tst = d.fund_quote_crny
                     AND ci.member_descr_tst = 'O')
UNION ALL
--for member_descr = 'O' and if the fund_isin exist in one table but not in another then take those rows(bidirectional)
--exists in IS_ID_TST and not in IS_ID
SELECT d.fund_isin_tst,d.fund_quote_crny_tst,d.member_descr_tst,d.member_ratio_tst,d.allocationassettype_tst
  FROM combined_data d
WHERE d.member_descr_tst = 'O'
  AND NOT EXISTS (SELECT 1
                    FROM combined_data ci
                   WHERE ci.fund_isin = d.fund_isin_tst
                     AND ci.fund_quote_crny = d.fund_quote_crny_tst
                     AND ci.member_descr = 'O')
UNION ALL
--for all the rows where member_descr ! = 'O',take all those rows from table IS_ID_TST
SELECT d.fund_isin_tst,d.allocationassettype_tst
  FROM combined_data d
WHERE d.fund_isin_tst IS NOT NULL
  AND (d.member_descr_tst != 'O' OR d.member_descr_tst IS NULL);