Question

I am attempting to convert a SQL stored procedure to LINQ to do some performance testing (trying to figure out if using LINQ in some of our methods will speed things up at all)

I am fairly new to doing anything in LINQ so I am just modifying examples in books / online to suit my needs and am stuck on something.

I have this code so far:

DIM TicketID as INTEGER = 1

DIM s = 
FROM User in PersonnelTbl 
WHERE !(from t in tblSupportTicketNotifications where t.TicketID = TicketID select t.EmployeeID).Contains(User.EmployeeID)
Select user

Im not sure why but I get an Identifier expected error message on the Where clause line. Can anyone point me in the right direction? Cheers

I’ve based my code so far on this example:

var query = 

    from c in dc.Customers 

    where !(from o in dc.Orders 

            select o.CustomerID)

           .Contains(c.CustomerID) 

    select c;

This is what I am trying to convert

CREATE PROCEDURE spGetEmployeesToBeNotified  
(  
 @TicketID INT  
)  
AS   
BEGIN  

 SELECT   
  ID,   
  FirstName,  
  Surname,  
  FirstName+' '+Surname As FullName,   
  WorkEmail,   
  0 AS Checked  
 FROM   
  PersonnelTbl   
 WHERE   
  ID NOT IN(SELECT EmployeeID FROM tblSupportTicketNotifications WHERE TicketID = @TicketID)  
 AND  
  (FirstName IS NOT NULL   
  AND   
   FirstName <> ''   
  AND   
   Surname IS NOT NULL   
  AND   
   Surname <> '')  

 UNION  
 SELECT   
  person.ID,  
  person.FirstName,  
  person.Surname,  
  person.FirstName +' '+person.Surname As FullName,  
  person.WorkEmail,  
  1 AS Checked  
 FROM  
  PersonnelTbl person  
 JOIN  
  tblSupportTicketNotifications notify  
 ON  
  person.ID = notify.EmployeeID  
 WHERE  
  TicketID = @TicketID  
 ORDER BY   
  FirstName ASC,   
  Surname ASC  
END

Answer 1

Assuming you have an association between User and SupportTicketNotifications, you could try the following which should use an Exists clause rather than In. You can then profile the differences in SQL to see which one actually works faster (or if the SQL engine optimizes them to the same things.)

DIM TicketID as INTEGER = 1 

DIM s =  
FROM User in PersonnelTbl  
WHERE Not User.SupportTicketNotifications.Any(Function(t) t.TicketID = TicketID)

' The Select is optional in VB if you are just returning the item you are selecting.

Regarding performance with LINQ to SQL as compared to raw ADO, you may want to check out http://blogs.msdn.com/ricom/archive/2007/06/22/dlinq-linq-to-sql-performance-part-1.aspx. As you are learning LINQ, you should make an effort to profile what you are doing in any regard to help you learn what’s happening and where you need to make performance improvements (including using Stored Procs/custom ADO where necessary).