Question

I’m not sure if an answer for this already exists, as I can’t figure out what mechanism in Linq is meant for this situation, or if I just need to do it manually.

Let’s say I have 2 tables:

------------Employees------------- EmployeeID  Name  -other columns-     ---------EmployeeSkills-----------    EmployeeID  Skill  -other columns- 

So each employee can have 0 or more skills.

My goal is to draw this information into a data structure in memory, using one sql query

    class StaticEmployee     {         int EmployeeID;                string Name;         List<string> Skills;     }     List<StaticEmployee> employees = (???).ToList(); 

Since my table relations are setup, I could just foreach the employees table (from employee in db.Employees select employee), however when I access the EmployeeSkills property, it is going to execute a seperate query for every employee record since that data wasn’t returned with the first query.

Alternatively, and I what I want done so far as Sql is concerned, is run a query with a left join:

SELECT Employees.EmployeeID, Employees.Name, EmployeeSkills.Skill FROM Employees LEFT JOIN EmployeeSkills ON Employees.EmployeeID=EmployeeSkills.EmployeeID 

That will get me my list, but I’ll need to manually collate it into my list since an employee with 2 skills will return 2 rows. Is there a Linq operation that does this? Hypothetical example below

from employee in db.Employees select new  {    EmployeeID = employee.EmployeeID,     Name = employee.Name,    Skills = new List(                      from employeeSkill in employee.EmployeeSkills                       select employeeSkill.skill                     ) } 

Answer 1

var options = new DataLoadOptions(); options.LoadWith< Employees>(e => e.EmployeeSkills); context.LoadOptions = options; //retrieve employees, they will come loaded with EmployeeSkills 

If you were to use the linq query version instead, this will load them once as well:

from employee in db.Employees select new  {    EmployeeID = employee.EmployeeID,     Name = employee.Name,    Skills = employee.EmployeeSkills }