SQL：需要为每个单个记录创建两个唯一记录

Question

The simple question is how can you take a set of records with a PK and create exactly two records for each source with a slightly altered key for the duplicate? In other words, I take 4000 records and produce 8000 records where 4000 are identical and the other 4000 have a slightly altered key. I cannot do a union because this is essentially two selects (long story).

The rest gets complicated, but maybe necessary to provide examples.

This is my original set (it contains over 4000 records)

dateGroup areaGroup itemID editionID
   1          1        1       1
   1          1        1       2
   1          2        1       1
   1          2        2       1

   2          1        1       1
   2          1        1       2
   2          2        1       1
   2          2        1       2

For each record I need to create a duplicate record ganging the areaGroups together under '0', then create a comma separated list of original areaGroups as a separate field. (The "why" is some dumb programmer (me) made a mistake about 15 years ago.) I can renumber the editionIDs as necessary, but the original and duplicate record must have the same editionID (thus why a union wouldn't work). The PK remains the same as above (all fields)

dateGroup areaGroup itemID editionID aGroups
   1          0        1       1        1
   1          0        1       2        1
   1          0        1       1        2    // Duplicate (EditionID)
   1          0        2       1        2
   2          0        1       1        1
   2          0        1       2        1
   2          0        1       1        2    // Duplicate (EditionID)
   2          0        1       2        2

The end result would renumber the editionID as needed to make the record unique.

dateGroup areaGroup itemID editionID aGroups  (EditionID is what is altered)
   1          0        1       1        1
   1          0        1       2        1
   1          0        1       2        2    1 changed to 2 (one more than row 1)
   1          0        2       1        2
   2          0        1       1        1
   2          0        1       2        1
   2          0        1       2        2    1 changed to 2 (one more than row 1)
   2          0        1       2        2

   1          1        1       1
   1          1        1       2
   1          2        1       2             1 changed to 2 (editionID) to match
   1          2        2       1

   2          1        1       1
   2          1        1       2
   2          2        1       2             1 changed to 2 to match above
   2          2        1       2

I know you could calculate the editionID like a row rank like so:

select row_number() over ( 
       partition by dateGroup, itemID 
       order by dateGroup, itemID) as editionID

So all I need is to know how to duplicate the records from a single set

Answer 1

在派生表上进行交叉联接：（选择1作为aGroups并全部选择2）

Answer 2

I'd create a temporary table with duplicates and their count. Then I'd filter the original table to have only unique rows, and insert another row for each row in the temporary table, incrementing their editionID.

In MySQL, I'd use user @variables; not sure about MS SQL.

Answer 3

Did you try UNION ALL instead of just UNION

UDPATE perhaps I misunderstood the problem and I thought you were having a problem with the union loosing the duplicates.

If the problem is that you want to do a row_number over a union why don't you do somthing like

select row_number() over ( 
       partition by dateGroup, itemID 
       order by dateGroup, itemID) as editionID
FROM
(

         SELECT 

              dateGroup, itemID
          FROM TableA
          UNION ALL 
         SELECT 

              dateGroup, itemID
          FROM TableB 
) Data