CODEWITHSUNDEEP
sql-servergroup-bysum
GLP
GLP

Reputation: 3675

how to sum conditionally?

I have a following table

Col1   Col2   Col3
A1     1      null
A1     2      null
B1     5      null
B2     6      null
M1     1      M
M2     2      M
M3     3      M
J1     1      J
J2     2      J

I want to sum Col2 based on Col1. The query will be like following,

select Col1, sum (Col2)
group by Col1

However, if Col3 has the same letter, I want sum up Col2 for all Col1. So the result table should be like

Col1    Col2 
A1      3
B1      5
B2      6
M1      6
M2      6
M3      6
J1      3
J2      3

How do I change my query to get above table?

Upvotes: 3

Views: 126

Answers (2)

TEEKAY
TEEKAY

Reputation: 1186

Edit after comment / update to question. I didn't know a clever way, seems like some others have one though.

select * from (
select Col1, SUM(Col2) Col2
from Table
where Col3 is null
group by Col1

union

select mainset.Col1, tmp.Col2
from Table mainset
join 
(
    select Col3, SUM(Col2) Col2
    from Table
    where Col3 is not null
    group by Col3
) tmp on tmp.Col3 = mainset.Col3

where mainset.Col3 is not null
) fullset
order by fullset.Col1

Upvotes: 1

Jason Whitish
Jason Whitish

Reputation: 1438

You could do something like this (I named the table #a):

    ;WITH col3Sum AS
    (
        SELECT Col3, SUM(Col2) SUM3
        FROM #a
        WHERE col3 IS NOT NULL
        GROUP BY col3
    ),
        col1Sum AS
    (
        SELECT Col1, SUM(Col2) sum1
        FROM #a 
        GROUP BY Col1
    )   
    SELECT c1.Col1, ISNULL(c3.SUM3, c1.sum1) AS Col2
    FROM col1Sum c1
    LEFT JOIN col3Sum c3
        ON c1.Col1 LIKE c3.Col3+'%'
    ORDER BY c1.Col1

Upvotes: 0

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