SQL 挑战

Question

how are you today?

After burn a few neurons with part of my requirement, I'm forced to ask for your help

I would like to solve this with pure SQL sentences in an AMDP method, I could solve this easily in ABAP, even in an AMDP method using loops, but as I said, I would like to solve this with SQL sentences, without use any kind of loops.

Please take a look on this image:

Sample

I have 2 columns, the first I'll name as D and the second as E

The D column, is a result of a SELECT SUM, but the E colunm, is a calculated column, and it shoud work as follow:

Firsrt line are equals in both columns. **E1 = D1**
In the second line, the calculation for the second column is **E1 + D2**
In the third line, the calculation for the second column is **E2 + D3**
In the forth line, the calculation for the second column is **E3 + D4**
And so on.

So thats it. Is it posible solve this with pure SQL sentences?

Could someone please give me a help?

Best regards.

Ronaldo S. Vieira

Answer 1

Have the SUM in a subquery, then do a select from that subquery along with a row number. Insert that into a temporary table. Then select from that temporary table and do a join to the same table based on the row number, looking for the previous row.

SELECT D, ROW_NUMBER() AS ROW_NUM
INTO #TempTable
FROM (SELECT SUM() AS D FROM table) a

SELECT
    t1.D
    ,CASE
        t2.D IS NULL THEN t1.D
        ELSE t2.D + t1.D AS E
FROM #TempTable t1
    LEFT JOIN #TempTable t2 ON t1.ROW_NUM = t2.ROW_NUM + 1