Question

im using vs2010 and have a sql statment shown below

select deptId, deptName, Detail from lkDept where deptId in (select deptId from lkDeptLinks where userRef in (select ref from lkUsers where userId = @userId)) order by deptName

i need the above converted to a linq statement, lambda would be nice

all tables are in the dbml

this is the mess i have so far, obviously it wont work

var queryUsers = dc.lkUsers.Where(p => p.UserID == userId);
var queryLinks = dc.lkDeptLinks.Where(p => queryUsers.ref.contains(p.ref));
var queryDept = dc.lkDepts.Where(p => queryLinks.deptid.contains(p.deptid));

any help would be apprieciated and thanks in advance

---

ok thanks guys for your help, i ended up with somethign like this

  using (var dc = new myDataContext(DB.GetConnectionString()))
  {
      var queryUsers = dc.lkUsers.Where(p => p.UserID == userId).Select(p => p.@ref); 
      var queryLinks = dc.lkDeptLinks.Where(p => queryUsers.Any(x => p.UserRef  == x )).Select(p => p.DeptId);
      var queryDept = dc.lkDepts.Where(p => queryLinks.Any(x => p.DeptID == x)).OrderBy(p => p.deptName).Select(p => new SLDepartment(p));

      if (queryDept.Any())
        return new SLDepartments(queryDept);

  }

note the constructors , SlDepartment(lkDept dept) and SlDepartments(IEnumerable collection) is this an appropriate way of working with LINQ?

any gotachas i might be missing, ie potentials for exceptions or perforamnce issues with the above or the whole solutions?

Answer 1

Your attempt seems correct but just should change contains -> Any and also is incomplete:

var queryUsers = dc.lkUsers.Where(p => p.UserID == userId);
var queryLinks = dc.lkDeptLinks.Where(p => queryUsers.ref.Any(x=>x== p));
var queryDept = dc.lkDepts.Where(p => queryLinks.deptid.Any(x=> x == p.deptid));
return  queryDept
        .Select(x=>new {ID = x.deptId, Name = x.deptName, Detail = x.Detail})
        .ToList();