CODEWITHSUNDEEP
c#linq-to-sql
Andy
Andy

Reputation: 2318

how to only query newest version?

The following query gives me a barcode, version no of that barcode and an appcode. I would need the query to filter out duplicate barcodes and only keep the highest version number of that barcode.

I've been thinking along the way of merging the barcode field and the version field and only keep the highest but that seems dirty. Is there a cleaner solution?

select Barcode, MAX(versionNo) vn, Appcode from Mailsort
where Created between '01/26/2011' and '01/27/2011'
group by Barcode, AppCode;

The reason for this query is to get a LINQ statement.This does a count for every appcode regardless of the barcodes or the version at thye moment.

var results = from p in dataContext.GetTable<mailsortEntity>()
              where p.Created > datetime && p.Created < datetime.AddDays(1)
              group p by new { p.AppCode } into g
              select new AppCodeCountEntity
              {
                  AppCode = g.Key.AppCode,
                  Count = g.Count()
              };

Is there a better solution than this LINQ code above?

Upvotes: 0

Views: 73

Answers (1)

JohnOpincar
JohnOpincar

Reputation: 5813

var maxQuery = 
 from rh in MailSort
 group rh by rh.BarCode into latest
 select new { BarCode = latest.Key, MaxVersion = latest.Max(l => l.Version) }
;

var query = 
 from rh2 in MailSort
 join max in maxQuery on new {rh2.BarCode, Version = rh2.Version } 
  equals new { max.BarCode, Version = max.MaxVersion }
 select new { rh2.BarCode, rh2.Version, rh2.AppCode }
;

var barCodes = query.ToList();

Upvotes: 1

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