T-SQL to LINQ conversion

Question

I have the following SQL statement

SELECT 
    c.CorpSystemID, c.SystemName  , 
    case when a.TaskItemID is NULL then 'false' else 'true' end as Assigned
FROM CorpSystems c 
LEFT OUTER JOIN
     (SELECT CorpSystemID, TASKItemID 
      FROM AffectedSystems 
      where TASKItemID = 1) a ON c.CorpSystemID = a.CorpSystemID

Can anyone please help me to convert this statement to LINQ?

Thank you.

Answer 1

Ok so assume you've got a list of your CorpSystem objects in a variable called Corpsystems and a list of your AffectedSystem objects in a variable called AffectedSystems. Try the following:

Edit: For a join on all Affected Systems, try this:

var matches = from c in CorpSystems
              join a in AffectedSystems on c.CorpSystemId equals a.CorpSystemId into ac
              from subSystem in ac.DefaultIfEmpty()
              select new
                     {
                         c.CorpSystemId,
                         c.SystemName,
                         Assigned = subSystem != null && subSystem.TaskItemId != null
                     };

Or for just AffectedSystems that have a TaskItemId of 1:

var matches = from c in CorpSystems
              join a in AffectedSystems.Where(as => as.TaskItemId == 1)
                  on c.CorpSystemId equals a.CorpSystemId into ac
              from subSystem in ac.DefaultIfEmpty()
              select new
                     {
                         c.CorpSystemId,
                         c.SystemName,
                         Assigned = subSystem != null && subSystem.TaskItemId != null
                     };

Answer 2

See the answers to the following SO question SQL to LINQ Tool, assuming that you do not want to go through the process by hand.