Question : Query to group sparse data?

Hello,

I have a customer that has come to me with a request for a query that I've never attempted before.

Certainly I could use VBA to get around doing it with SQL rather easily, but they want a SQL solution without altering the structure of their existing table.

Here is the table layout:

ID Column1 Column2 Column3 Column4 Column5 ...etc...
1 0 0 5 0 0
2 7 0 0 2 0
3 1 2 3 0 0
...etc...

They want the query output to look like so:

ID Type1 Type2 Type3
1 5 0 0
2 7 2 0
3 1 2 3

I could also write a really long nasty chain of IIF statements, but i'm looking for something much more elegant. (There are about 30 columns)

Any thoughts?

-Torrwin

Answer : Query to group sparse data?

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With ee26366939 as the base table with ID, Col1, Col2, Col3, Col4, Col5
And two helper queries

q26366939:

SELECT
ID,
IIF(Col1=0,null,Col1) AS Col1a,
IIF(Col2=0,null,Col2) AS Col2a,
IIF(Col3=0,null,Col3) AS Col3a,
IIF(Col4=0,null,Col4) AS Col4a,
IIF(Col5=0,null,Col5) AS Col5a
FROM ee26366939;

q26366939a:

SELECT
ID,
nz(Col1a/Col1a,0) as Col1b,
nz(Col1a/Col1a,0)+nz(Col2a/Col2a,0) as Col2b,
nz(Col1a/Col1a,0)+nz(Col2a/Col2a,0)+nz(Col3a/Col3a,0) as Col3b,
nz(Col1a/Col1a,0)+nz(Col2a/Col2a,0)+nz(Col3a/Col3a,0)+nz(Col4a/Col4a,0) as Col4b,
nz(Col1a/Col1a,0)+nz(Col2a/Col2a,0)+nz(Col3a/Col3a,0)+nz(Col4a/Col4a,0)+nz(Col5a/Col5a,0) as Col5b
FROM q26366939;

The final query can be written thus:

SELECT
A.ID,
IIF(Col1B=1,Col1,IIF(Col2b=1,Col2,IIF(Col3b=1,Col3,IIF(Col4b=1,Col4,Col5)))),
IIF(Col1B=2,Col1,IIF(Col2b=2,Col2,IIF(Col3b=2,Col3,IIF(Col4b=2,Col4,Col5)))),
IIF(Col1B=3,Col1,IIF(Col2b=3,Col2,IIF(Col3b=3,Col3,IIF(Col4b=3,Col4,Col5)))),
IIF(Col1B=4,Col1,IIF(Col2b=4,Col2,IIF(Col3b=4,Col3,IIF(Col4b=4,Col4,Col5)))),
IIF(Col1B=5,Col1,IIF(Col2b=5,Col2,IIF(Col3b=5,Col3,IIF(Col4b=5,Col4,Col5))))
FROM ee26366939 AS A
inner join q26366939a As B on A.ID=B.ID;