Oracle SQL 带条件的合并语句

Question

我对 SQL 比较陌生，我遇到了目标表未更新的问题。我有重复的帐户 #（键），在相关列中具有不同的联系信息。我正在尝试合并联系信息（源）进入单行/帐号，不重复的联系信息进入（目标）扩展列。

我构造了一个带有 case 条件的 Merge 语句来检查数据是否存在于目标表中。 如果数据不在目标表中，则在扩展列中添加信息。 问题是目标表没有得到更新。 源表和目标表都是相似性定义的。

**Merge SQL- reduced query**
MERGE INTO target tgt
    USING (select accountno, cell, site, contact, email1 from (select w.accountno, w.cell, w.site, w.contact, email1, row_number() over (PARTITION BY w.accountno order by accountno desc) acct 
    from source w) inn where inn.acct =1) src 
    ON (tgt.accountno = src.accountno)
WHEN MATCHED
    THEN 
        UPDATE SET
                  tgt.phone4 =  
                  CASE WHEN src.cell <> tgt.cell
                  THEN src.cell
                  END,
                  tgt.phone5 =
                  CASE WHEN src.site <> tgt.site
                  THEN src.site
                  END

我已验证源表中存在应添加到目标表中的 accountno 的联系信息。 我非常感谢任何关于为什么没有更新目标表的见解。 我在 Stack 上看到了类似的问题，但没有回复。

Answer 1

您在 using 子句中的 SRC 子查询为每个 accountno 仅返回 1 个随机行。 您需要聚合它们，例如使用 PIVOT：

with source(accountno, cell, site, contact) as ( --test data:
   select 1,8881234567,8881235678,8881236789 from dual union all
   select 1,8881234567,8881235678,8881236789 from dual
)
select accountno, contact, 
       r1_cell, r1_site, 
       r2_cell, r2_site
from (select s.*,row_number()over(partition by accountno order by cell) rn
      from source s
     )
pivot (
   max(cell) cell,max(site) site
    FOR rn
    IN (1 R1,2 R2)
)

所以最后你可以将 r1_cell、r1_site、r2_cell、r2_site 与目标值进行比较并使用所需的值：

MERGE INTO target tgt
    USING (
            select accountno, contact, 
                   r1_cell, r1_site, 
                   r2_cell, r2_site
            from (select s.*,row_number()over(partition by accountno order by cell) rn
                  from source s
                 )
            pivot (
               max(cell) cell,max(site) site
                FOR rn
                IN (1 R1,2 R2)
            )
          ) src 
    ON (tgt.accountno = src.accountno)
WHEN MATCHED
    THEN 
        UPDATE SET
                  tgt.phone4 =  
                  CASE 
                       WHEN src.r1_cell <> tgt.cell 
                          THEN src.r1_cell
                          ELSE src.r2_cell
                  END,
                  tgt.phone5 =
                  CASE WHEN src.r1_site <> tgt.site 
                     THEN src.r1_site
                     ELSE src.r2_site
                  END
/

Answer 2

问题在于您在 row_numbering 具有相同 account_number 的行中使用的逻辑。

MERGE 
 INTO target tgt
USING (select accountno, cell, site, contact, email1 
         from (select w.accountno, w.cell, w.site, w.contact, email1
                    , row_number() over (PARTITION BY w.accountno order by w.accountno desc) acct 
                from source w
              left join target w2
                  on w.accountno=w2.accountno
               where w2.cell is null /* get records which are not in target*/ 
              ) inn 
         where inn.acct =1
       ) src 
   ON (tgt.accountno = src.accountno)
WHEN MATCHED THEN 
     UPDATE 
        SET tgt.phone4 = src.cell,
            tgt.phone5 = src.site