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--1 задача 1 вариант select * from ( select job_id, department_id from employees where department_id = 10 union select job_id, department_id from employees where department_id = 20 union select job_id, department_id from employees where department_id = 50 ) t order by case department_id when 10 then 1 when 50 then 2 when 20 then 3 end; --1 задача 2 вариант select * from ( select job_id, department_id from employees where department_id is not null minus select job_id, department_id from employees where department_id not in (10,20,50) )t order by case department_id when 10 then 1 when 50 then 2 when 20 then 3 end; --1 задача 3 вариант select * from ( select job_id, department_id from employees intersect select job_id, department_id from employees where department_id in (10,20,50) )t order by case department_id when 10 then 1 when 50 then 2 when 20 then 3 end; --2 задача select EMPLOYEE_ID, LAST_NAME from ( select EMPLOYEE_ID, LAST_NAME, max(instr(LAST_NAME, 'u')) over(partition by DEPARTMENT_ID) flag from employees )t where flag > 0 order by 1;