Losing Aliases when trying to group-by rows in linq sql query, how to group-by rows in this case - sql

Question

I am a newbie intern way over my head, I promise I have researched this thoroughly and tried many different things. The following linq query works, but I want to group rows by last and first name and then only show the rows that appear more than once. When I un-comment out the group by statement, all my aliases below become unrecognized and changing them to the actual db.table names doesn't help.
var query = from emps in db.Employees
join c in db.Cards on emps.SbiID equals c.SbiID
where c.StateID == 0 && c.CardNumberNumeric > 100000
//group emps by new {emps.Surname, emps.Name};
//orderby grp.Count() // something like 'where grp.Count > 1
select new
{
Surname = emps.Surname,
Name = emps.Name,
CorpID = emps.Identifier,
CardNum = c.CardNumber,
CostCenter = emps.EmployeeUserField.UF13,
Supervisor = (from e in db.Employees
where
e.Identifier.Equals(emps.EmployeeUserField.UF5)
select e.Surname).FirstOrDefault()
+ ", "
+ (from e in db.Employees
where e.Identifier.Equals(emps.EmployeeUserField.UF5)
select e.Name).FirstOrDefault(),
SupervisorID = emps.EmployeeUserField.UF5,
EmpCommence = emps.CommencementDateTime,
CardCommence = c.CommencementDateTime,
WorkPhone = emps.Telephone,
State = (from cf in db.ComboFields
from sp in db.StringProperties
where cf.ComboIndex.Equals(c.StateID)
&& cf.StringID.Equals(sp.StringID)
&& cf.TableName.Equals("Card")
&& cf.FieldName.Equals("StateID")
select sp.DefaultValue).FirstOrDefault()
};
this.tagsGridView.DataSource = query;
this.tagsGridView.DataBind();

Answer 1

I think the problem you're running into is that you're not flattening out your groups appropriately. For example:
var duplicateEmployees = db.Employees
.GroupBy(emp => emp, new EmployeeComparer())
.Where(grp => grp.Count() > 1)
.SelectMany(grp => grp.AsEnumerable());
var duplicateEmployeeInfo =
from emps in duplicateEmployees
join c in db.Cards on emps.SbiID equals c.SbiID
where c.StateID == 0 && c.CardNumberNumeric > 100000
select new
{
... what to select
};
With:
public class EmployeeComparer : IEqualityComparer<Employee>
{
public bool Equals(Employee x, Employee y)
{
return x.Surname == y.Surname && x.Name == y.Name;
}
public int GetHashCode(Employee obj)
{
unchecked { return (17 * obj.Surname.GetHashCode()) ^ (23 * obj.Name.GetHashCode()); }
}
}
This groups the employees by name, finds the groups that have a count > 1, then returns the elements of those groups. No guarantees on performance, but this should solve your issue.