SQL to OQL

Here are some examples.  Keep in mind that with OQL the persistence manager returns entities, not single values.

        public IEnumerable<Employee> GetEmployeesManagedBy(Employee manager) {
            var query = new EntityQuery(typeof(Employee));
            query.AddSubquery(EntityRelations.Department_Employee_Works_In.ToParent);
            query.AddClause(Department.ManagerEmployeeIdEntityColumn, EntityQueryOp.EQ, manager.EmployeeId);
            return persistenceManager.GetEntities<Employee>(query);
        }

        public IEnumerable<Employee> GetEmployeesManagedBy(long managerId) {
            var query = new EntityQuery(typeof(Employee));
            query.AddSubquery(EntityRelations.Department_Employee_Works_In.ToParent);
            query.AddClause(Department.ManagerEmployeeIdEntityColumn, EntityQueryOp.EQ, managerId);
            return persistenceManager.GetEntities<Employee>(query);
        }

        public IEnumerable<Employee> GetEmployeesManagedBy(string managerName) {
            var names = managerName.Split(' ');
            var query = new EntityQuery(typeof(Employee));
            query.AddSubquery(EntityRelations.Department_Employee_Works_In.ToParent);
            query.AddSubquery(EntityRelations.Employee_Manager_For_Department.ToChild);
            query.AddClause(Employee.FirstNameEntityColumn, EntityQueryOp.EQ, names[0]);
            query.AddClause(Employee.LastNameEntityColumn, EntityQueryOp.EQ, names[1]);
            return persistenceManager.GetEntities<Employee>(query);
        }

Notice that DevForce returns a collection of Employees and not the result of a join.  If you want your result to contain columns from related tables, you should review the material on Dynamic Entities.  However, in most circumstances, we prefer that you avoid the use of Dynamic Entities as they are more complicated to use and do not work well in environments which require modification, deletion, or insertion.