SQL高级部分一(SET运算符 && 高级子查询)

select employee_id , department_id
from emp01
union all --相当于两个集合相加， union A并B ，intersect ，A交B，MINUS 差集，A-B
select employee_id , department_id
from emp02

SELECT department_id, TO_NUMBER(null) location, hire_date
FROM   employees
UNION
SELECT department_id, location_id,  TO_DATE(null)

FROM   departments;

SELECT employee_id, job_id,salary
FROM   employees
UNION
SELECT employee_id, job_id,0 --salary可以用0代替
FROM   job_history;

指定列不显示column 指定列的名字 noprint;

SELECT 'sing'  "My dream", 3 a_nu
FROM dual
UNION
SELECT 'I`d like to teach',1
FROM dual
UNION 
SELECT 'the world to',1
FROM dual
order by 2

select manager_id , employee_id,department_id
from employees
where (manager_id,department_id) in (
                                   select manager_id,department_id
                                   from employees
                                   where employee_id in (141,174)
                                    )
and employee_id not in(141,174)

SELECT  employee_id, manager_id, department_id
FROM    employees
WHERE   manager_id IN  (
			SELECT  manager_id
 
	                FROM    employees
	
                WHERE   employee_id IN (174,141)
			)
AND   department_id IN  (
			SELECT  department_id
                        FROM    employees
		        WHERE   employee_id IN (174,141)
			)
AND employee_id NOT IN(174,141);

select last_name,department_id,salary,
(select avg(salary)from employees e3 
where e1.department_id = e3.department_id 
group by department_id) avg_salary
from employees e1
where salary >     
	(select avg(salary)
          from employees e2
          where e1.department_id = e2.department_id
          group by department_id
          )

select employee_id , e1.department_id , salary ,e2.avg_sal
from employees e1 , (select department_id , avg(salary) avg_sal
                    from employees
                    group by department_id
                    ) e2 --以子查询的形式，形成了一个新表
where e1.department_id = e2.department_id
and e1.salary > e2.avg_sal

/*select employee_id , last_name , (
                                 case department_id 
                                 when (select department_id
                                       from departments
                                       where location_id = 1800
                                       )
                                 then 'Canada' else 'Usa'
                                 end
                                 ) location
from employees
*/
SELECT employee_id, last_name,
       (CASE
        WHEN department_id =
                (select department_id 
                from departments
                where location_id = 1800
                 )
        THEN 'Canada' ELSE 'USA' END) location
FROM   employees

SELECT   employee_id, last_name
FROM     employees e
ORDER BY (SELECT department_name 
	FROM departments d 
	WHERE e.department_id = d.department_id
	);

SELECT column1, column2, ...
FROM   table1
 outer
WHERE  column1 operator
			(SELECT  colum1, column2
                      FROM    table2
                       WHERE   expr1 = outer.expr2);

select employee_id , last_name , job_id 
from employees e
where 2 <= (
               select count(*)
               from job_history j
               where e.employee_id = j.employee_id 
           )

/*
select employee_id , last_name , salary
from employees e1
where e1.employee_id in(
                   select manager_id
                   from employees e2
                   )
*/
/*
select distinct e1.employee_id , e1.last_name , e1.salary
from employees e1,employees e2
where e1.employee_id = e2.manager_id
*/
SELECT employee_id, last_name, job_id, department_id
FROM   employees outer
WHERE  EXISTS ( SELECT 'X'
                 FROM   employees
                 WHERE  manager_id = outer.employee_id     
		);

/*
select d1.department_id
from departments d1
minus
SELECT department_id
 FROM   employees
*/
SELECT department_id, department_name
FROM departments d
WHERE NOT EXISTS (
		SELECT 'X'
                  FROM   employees
                  WHERE  department_id  = d.department_id
		);  

SQL高级部分一(SET运算符 && 高级子查询)

原文：http://blog.csdn.net/wjw0130/article/details/43818679