Question

Based on the following tables

Sample
Id     Name
---------------
S1     SomeName
S2     OtherName
S3     AnotherName

AlreadyUsed
Id
---------
S2

Reference
Id    FkId
---------
T1    S1
T2    S1

I want to achieve the following
“select only those entries from Sample table which have no entries in AlreadyUsed and have atleast one entry in
Reference table.”

I was able to write query for the first part but confused with the second half. Below is what i could come up with to get “select only those entries from sample table which have no entries in AlreadyUsed table”

var count = 50;

var alreayUsed = from au in repository.GetEntity<AlreadyUsed>() 
                 select au.Id;

var notUsed = (from nu in repository.GetEntity<Sample>()
              where !alreadyUsed.Contains(nu.Id)
              orderby nu.Name
              select new CustomClass
              {
                 CName = nu.Name,
                 CId = nu.Id
              }).Take(count).ToArray();

Also pls. suggest if there is a better way to write the above query.

thanks.

Answer 1

var count = 50;

var alreayUsed = from au in repository.GetEntity<AlreadyUsed>() 
                 select au.Id;

var notUsed = (from nu in repository.GetEntity<Sample>()
              where !alreadyUsed.Contains(nu.Id) && nu.References.Count() > 0
              orderby nu.Name
              select new CustomClass
              {
                 CName = nu.Name,
                 CId = nu.Id
              }).Take(count).ToArray();

Notice that I added “nu.References.Count() > 0”

I assume that you setup the association relationship called References correctly in your data model so that there are many “Reference” objects in for every Sample object.