30RM215w

1-- borrowed from https://stackoverflow.com/q/7745609/808921
2
3CREATE TABLE IF NOT EXISTS `customer` (
4  `name` varchar(90)  NOT NULL,
5  `item` varchar(90)  NOT NULL
6) DEFAULT CHARSET=utf8;
7INSERT INTO `customer` (`name`, `item`) VALUES
8  ('1', '1'),
9  ('1', '3'),
10  ('3', '1'),
11  ('3', '3'),
12  ('2', '1'),
13  ('2', '3'),
14  ('3' ,'2'),
15  ('3' ,'1'),
16  ('4', '1'),
17  ('4', '3'),
18  ('4', '7')
19
20
21
22
23
24select item , count(item) as pp from 
25(select  name,item ,count(item) from customer group by name,item) as p
26group by item
27having count(item) = (select count( distinct name) from customer)