SQL query for parent with specific values in child set

问题

I am trying to return just the parent where the set of children contain multiple specific records. Given this table:

Product   State
-------   -----
111       AZ
111       CA
111       UT
222       AZ
222       WA
333       CA

I want find the list of Product that have both a AZ child record and a CA child record, even if it also has other records. Which would return ...

Product
-------
111

回答1:

select product  
  from table 
 where state in ('az','ca')  
 group by product 
having count(distinct(state)) = 2


select distinct product  
  from table 
 where state = 'az'
INTERSECT 
select distinct product  
  from table 
 where state = 'ca'  


select distinct t1.product  
  from table t1 
  join table t2 
    on t1.product = t2.product 
   and t1.state = 'az'
   and t2.state = 'ca'

The last is probably going to be the most efficient.

回答2:

SELECT product 
FROM table 
GROUP BY product 
HAVING SUM(CASE WHEN State 'AZ' THEN 1 ELSE 0 END) > 1
   AND SUM(CASE WHEN State 'CA' THEN 1 ELSE 0 END) > 1

来源：https://stackoverflow.com/questions/24332675/sql-query-for-parent-with-specific-values-in-child-set