Oracle MERGE statement error (ORA-30926)

问题

I inherited an Oracle script running on Oracle 11g that contains the following MERGE statement:

MERGE INTO MainTable PR
     USING IncrementalTable PRA
       ON (PR.contract = PRA.contract
       and PRA.memberType = 'Parent' )
     WHEN MATCHED THEN
       UPDATE SET PR.address1 = PRA.address1,
                  PR.city = PRA.city,
                  PR.state = PRA.sate,
                  PR.zipCode = PRA.zipCode,
                  PR.countryCode = PRA.countryCode
WHERE address1 IS NULL
  AND PR.memberType <> 'Parent'
;

As far as I can see, this is simply updating the child's address in MainTable from the parent's address in IncrementalTable. Unfortunately, when I run the statement, it throws the following error:

ORA-30926: unable to get a stable set of rows in the source tables

So, it looks like it can't find a distinct match in IncrementalTable with which to update. Querying the data, that appears to be the case:

select contract,
       memberType,
       count(*)
  from IncrementalTable
 group by contract,
       memberType
having count(*) > 1
;

CONTRACT               MEMBERTYPE   COUNT(*)
---------------------- ---------- ----------
1119839490             PARENT              2
7271122516             PARENT              2
1004798721             PARENT              2

Looking at the details of one of those contracts:

select *
  from IncrementalTable
 where contract = '1119839490'
   and memberType = 'Parent'
;


CONTRACT               MEMBERTYPE ADDRESS1          CITY                           STATE ZIPCODE   COUNTRYCODE
---------------------- ---------- ----------------  ------------------------------ ----- -------   -----------
1165439488             Parent     1234 Dorioth St   Orlando                        FL    32825     USA
1165439488             Parent     1234 Dorioth St   Orlando                        FL    32825     USA

So, how can I merge only the DISTINCT match from IncrementalTable?

Thanks in adavnce for your help!

回答1:

The first (and most obvious) answer is to clean up the data so you don't have duplicates. It seems likely that the sample data you provided is the result of a bug.

As for the merge statement, if the data is actually purely duplicated, you can just use distinct:

MERGE INTO maintable pr
USING      (SELECT DISTINCT contract,
                            membertype,
                            address1,
                            city,
                            state,
                            zipcode,
                            countrycode
            FROM   incrementaltable pra
            WHERE  pra.membertype = 'Parent')
ON         (pr.contract = pra.contract)
WHEN MATCHED THEN
   UPDATE SET pr.address1 = pra.address1,
              pr.city = pra.city,
              pr.state = pra.sate,
              pr.zipcode = pra.zipcode,
              pr.countrycode = pra.countrycode
      WHERE      address1 IS NULL AND pr.membertype <> 'Parent'

来源：https://stackoverflow.com/questions/28636860/oracle-merge-statement-error-ora-30926

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Oracle

oracle11g