Is there any other way to write the following code

Question

I have a code like this -

//there i get all the Jaipur city employee list
List<Employee> employeeList = [select ID from Employee where city='Jaipur'];

Now i need to get Departments of these Employees. I do like -

List<ID> idsList = new List<ID>();

//Iterate employeeList to get employee IDS 
for(Employee emp : employeeList){
    idsList.add(emp.id);
}

// Then get Department List of these ids
List<Department> departmentList = [select ID, name from Department where empId IN: idsList];

I need to ask Is there any other way to get Departments? i mean i don't want to iterate over employeeList to form idsList and then use those ids in next query to get departmentList.

can't i get IDS list directly from employeeList without iterating it completely?

Answer 1

I think u can use map instead of list like below

Map<id,Employee>  EmpMap = new Map<id,Employee>([select ID from Employee where city='Jaipur']);

and use this one in second query like

List<Department> departmentList = [select ID, name from Department where empId IN:EmpMap.keySet()];

Check below link for more details

http://developer.force.com/cookbook/recipe/initialising-maps-from-queries

Answer 2

List<Department> departmentList = [select ID, name from Department where empId IN (select ID from Employee where city='Jaipur')];

Here is other way of doing the same without iteration.