第六章 集合运算

use tsql2012;

select country, region, city from hr.employees

union all

select country, region, city from sales.customers;

select country, region, city from hr.employees

union

select country, region, city from sales.customers;

select country, region, city from hr.employees

intersect

select country, region, city from sales.customers;

select row_number() over(partition by country, region, city order by (select 0)) as rownum,

country, region, city

from hr.employees

intersect

select row_number() over(partition by country, region, city order by (select 0)) as rownum,

country, region, city

from sales.customers;

with intersect_all

as

(select row_number() over(partition by country, region, city order by (select 0)) as rownum,

country, region, city

from sales.customers

intersect

select row_number() over(partition by country, region, city order by (select 0)) as rownum,

country, region, city

from hr.employees)

select country, region, city from intersect_all;

select country, region, city from hr.employees

except

select country, region, city from sales.customers;

select country, region, city from sales.customers

except

select country, region, city from hr.employees;

with except_all

as

(select row_number() over(partition by country, region, city order by (select 0)) as rownum,

country, region, city

from hr.employees

except

select row_number() over(partition by country, region, city order by(select 0)) as rownum,

country, region, city

from sales.customers)

select country, region, city from except_all;

select country, count(*) as numlocations

from (select country, region, city from hr.employees

union

select country, region, city from sales.customers) as U

group by u.country;

select empid, orderid, orderdate

from (select top(2) empid, orderid, orderdate

from sales.orders

where empid = 3