Trying to combine multiple rows of result set into single row - sql

Question

select C.customerId,(C.lastName+', '+C.firstName) as CustomerName, C.companyName,
D.companyName+' ('+D.lastName+','+D.firstName+')'
as "Parent CompanyName(Last, First)",S.siteId, S.nickName as siteName,
dbo.GetSiteTelemetryBoxList(s.siteId) as "DeviceId's",
dbo.GetSiteTelemetryBoxSKUList(S.siteId,0) as SKU
from Site S
INNER JOIN Customer C ON S.customerId = C.customerId
INNER JOIN Customer D ON D.customerId = C.parentCustomerId
where S.createDate between DATEADD(DAY, -65, GETUTCDATE()) and GETUTCDATE()
order by C.customerId, S.siteId
The above query returns values that look like this:
CID CustomerName companyName Parent CompanyName(Last, First) SiteName DeviceId SKU
888296 DeYoung, Scott DeYoung Farms Mercier Valley Irrigation (Mercier,Ralph) H E east 200241 NETB12WR
890980 Rust, Marcus NULL Chester Inc. (Young,Scott) Byroad east 346370 NETB12WR
890980 Rust, Marcus NULL Chester Inc. (Young,Scott) Byroad west 345431 NETB12WR
891094 Pirani, Mark A Pirani Farm AMX Irrigation (Burroughs,Michael) hwy 64 south 333721 UNKNOWN
891094 Pirani, Mark A Pirani Farm AMX Irrigation (Burroughs,Michael) HWY 64 North 250162 NETB12WR
891094 Pirani, Mark A Pirani Farm AMX Irrigation (Burroughs,Michael) HWY 64 West 250164 NETB12WR
891094 Pirani, Mark A Pirani Farm AMX Irrigation (Burroughs,Michael) HWY 64 East 250157 NETB12WR
891430 Gammil, Bob Gammil FArms AMX Irrigation (Burroughs,Michael) angel 333677 UNKNOWN
891430 Gammil, Bob Gammil FArms AMX Irrigation (Burroughs,Michael) cemetery 333564 UNKNOWN
The problem I face now is that if a customerId/Name is repeating in the result set. The SiteName, deviceId, SKU should be concatenated to represent the data as one value.
For example, Mark Pirani row would look like
CID CustomerName ... SiteName DeviceId's ...
891904 Pirani, Mark ... hwy 64 south, HWY 64 North, HWY 64 West, HWY 64 East 333721,250162,250164,250157 ...

Answer 1

You can convert the rows with something like this to transform the rows into a concatenated string:
select
distinct
stuff((
select ',' + u.username
from users u
where u.username = username
order by u.username
for xml path('')
),1,1,'') as userlist
from users
group by username

Answer 2

I believe this is more of a SQL query issue than a C# code issue, or more appropriately I believe it more efficient to solve this problem at the query level rather than the code level. Off the top of my head you can use SELECT DISTINCT or GROUP BY clauses.
Here is another StackOverflow question addressing this issue - How do I (or can I) SELECT DISTINCT on multiple columns?

Answer 3

I did some digging and found a few ways to implement it. Basically, the simple solution for this is using mysql's group_concat function. These links discuss how the group_concat can be implemented for SQL server. You can choose one based on your requirements.
Simulating group_concat MySQL function in Microsoft SQL Server 2005? -- This thread discusses a few ways to implement it.
Flatten association table to multi-value column? -- This thread discusses the CLR implemenation of it.
http://groupconcat.codeplex.com/ -- This was just perfect for me. Exactly what I was looking for. The project basically creates four aggregate functions that collectively offer similar functionality to the MySQL GROUP_CONCAT function.