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哪位顧客訂購了最不同的書籍？顯示客戶ID幷包含關係。這不是在談論訂購的書籍數量。例如，假設我唯一的訂單是客戶1訂購了400份book_id 34客戶2訂購了2份book_id 62和3份book_id 29客戶1訂購了更多數量的書籍，但是客戶2訂購了更多不同的書籍。查詢應該 - 在這種情況下 - 返回客戶2：需要協助計算最不同的書籍
這是我的嘗試解決方案。不知道如何解決這個問題之一：
SELECT cust_id
FROM a_bkorders.customers
WHERE cust_id IN
(
SELECT cust_id
FROM a_bkorders.order_headers
Join a_bkorders.order_details using (order_id)
GROUP BY cust_id
HAVING count(book_id) <=
(
SELECT MAX(numBooks)
FROM (
SELECT cust_id
, count(book_id) AS numBooks
Join a_bkorders.order_details using (order_id)
FROM a_bkorders.order_headers
GROUP BY cust_id
) t
)
)ORDER BY cust_id;
下面是表：
-- create customers
create table a_bkorders.customers (
cust_id integer not null
, cust_name_last varchar(20) not null
, cust_name_first varchar(20) null
, cust_state char(2) not null
, cust_postal_code char(10) not null
, cust_acct_opened date not null
, constraint bk_cust_pk primary key (cust_id)
, constraint bk_cust_id_range check (cust_id > 1000)
, constraint bk_cust_acct_opened_ck check (cust_acct_opened >= '1975-01-01')
)engine = INNODB;
-- create order_headers
create table a_bkorders.order_headers (
order_id integer not null
, order_date date not null
, cust_id integer not null
, constraint bk_orders_pk primary key (order_id)
, constraint bk_orders_cust_fk foreign key(cust_id)
references a_bkorders.customers(cust_id)
, constraint bk_order_id_range check (order_id > 100)
, constraint bk_order_date_ck check (order_date >= '2000-01-01')
)engine = INNODB;
-- create order_details
create table a_bkorders.order_details (
order_id integer not null
, order_line integer not null
, book_id integer not null
, quantity integer not null
, order_price numeric(6,2) not null
, constraint bk_orderline_pk primary key (order_id, order_line)
, constraint bk_orderline_order_fk foreign key (order_id)
references a_bkorders.order_headers(order_id) on delete cascade
, constraint bk_orderline_book_fk foreign key (book_id)
references a_bkinfo.books(book_id)
, constraint bk_quantity_ck check (quantity > 0)
, constraint bk_ordprice_ck check (order_price >= 0)
)engine = INNODB;
這裏是插入：
-- customers
insert into a_bkorders.customers values (208950, 'Adams', 'Samuel', 'MA', '02106', '1996-04-15');
insert into a_bkorders.customers values (200368, 'Blake', 'William', 'CA', '95959', '1997-07-15');
insert into a_bkorders.customers values (258595, 'Jobs', 'Peter', 'MA', '02575', '1997-01-09');
insert into a_bkorders.customers values (263119, 'Jones', null, 'IL', '62979', '1997-03-02');
insert into a_bkorders.customers values (224038, 'Austin', 'Pat', 'CA', '95900', '1997-08-02');
insert into a_bkorders.customers values (255919, 'Milton', 'John', 'NJ', '08235', '2011-05-31');
insert into a_bkorders.customers values (211483, 'Carroll', 'Lewis', 'CA', '94203', '1998-08-08');
insert into a_bkorders.customers values (221297, 'Dodgson', 'Charles', 'MI', '49327', '2001-05-06');
insert into a_bkorders.customers values (261502, 'Hawthorne', 'Nathaniel', 'MA', '02297', '2001-10-12');
insert into a_bkorders.customers values (212921, 'Books on Tap', NULL, 'CA', '94112', '2002-01-06');
insert into a_bkorders.customers values (260368, 'Muller', 'Jonathan', 'IL', '62885', '2005-12-15');
insert into a_bkorders.customers values (259969, 'Carlsen', 'Benny', 'NJ', '08505', '2011-07-12');
insert into a_bkorders.customers values (239427, 'Marksa', 'Anna', 'NJ', '08495', '2011-02-28');
insert into a_bkorders.customers values (296598, 'Collins', 'Douglas', 'MO', '65836', '2005-04-25');
insert into a_bkorders.customers values (276381, 'Collins', 'Douglas', 'OH', '22451', '2005-02-08');
insert into a_bkorders.customers values (234138, 'Keats', 'John', 'IL', '61500', '2006-04-30');
insert into a_bkorders.customers values (267780, 'Shelly', 'Mary', 'CA', '94100', '2010-10-02');
insert into a_bkorders.customers values (290298, 'Swift', 'Jonathan', 'MI', '49201', '2010-10-12');
insert into a_bkorders.customers values (226656, 'Randall', 'Randell', 'NJ', '08251', '2011-08-08');
insert into a_bkorders.customers values (222477, 'Rossetti', 'Christina', 'MI', '49742', '2011-07-11');
insert into a_bkorders.customers values (227105, 'Kafka', 'Franz', 'MA', '02297', '2010-12-31');
insert into a_bkorders.customers values (202958, 'Denver', null, 'IL', '60405', '2011-01-15');
insert into a_bkorders.customers values (218709, 'Bonnard', 'Paul', 'MA', '02558', '2005-11-15');
insert into a_bkorders.customers values (217796, 'Anders', null, 'IL', '62505', '2011-03-30');
insert into a_bkorders.customers values (272787, 'Carlson', 'Ben', 'IL', '62505', '2011-05-05');
insert into a_bkorders.customers values (234709, 'Brahms', 'Johnnie', 'MA', '02558', '2012-01-15');
insert into a_bkorders.customers values (217002, 'Grieg', 'Edvard', 'IL', '62329', '2012-02-29');
insert into a_bkorders.customers values (272611, 'Jarrett', 'Keith', 'IL', '62329', '2011-11-11');
insert into a_bkorders.customers values (299099, 'Sam', 'Dave', 'CA', '94141', '2011-01-01');
insert into a_bkorders.customers values (259906, 'Capybara', 'Wile E.', 'CA', '94132', '2012-01-05');
insert into a_bkorders.customers values (259907, 'Hedge', 'Mr.', 'CA', '94132', '2011-09-05');
insert into a_bkorders.customers values (282716, 'Biederbecke','Dwight', 'PA', '18106', '2013-01-01');
insert into a_bkorders.customers values (287261, 'Biederbecke','Bix', 'PA', '18106', '2012-01-01');
insert into a_bkorders.customers values (226275, 'Dalrymple','Jack', 'SD', '57216', '2013-01-01');
insert into a_bkorders.customers values (228175, 'Cardin','Benjamin', 'MD', '20609', '2013-04-02');
insert into a_bkorders.customers values (228275, 'Mikulski','Barbara', 'MD', '21203', '2013-04-04');
insert into a_bkorders.customers values (228352, 'Edwards','Donna', 'MD', '21205', '2013-06-08');
-- orders and order_details
/* July 2011 */
Insert into a_bkorders.order_headers values(21841, '2011-07-02', 267780);
Insert into a_bkorders.order_details values(21841, 1, 1448, 50, 25.00);
Insert into a_bkorders.order_headers values(21850, '2011-07-02', 261502);
Insert into a_bkorders.order_details values(21850, 1, 1162, 1, 30.49);
Insert into a_bkorders.order_details values(21850, 2, 1109, 1, 25.00);
Insert into a_bkorders.order_headers values(2045, '2011-07-18', 267780);
Insert into a_bkorders.order_details values(2045, 1, 1894, 1, 35.99);
Insert into a_bkorders.order_headers values(2200, '2011-07-18', 261502);
Insert into a_bkorders.order_details values(2200, 1, 1200, 5, 16.33);
Insert into a_bkorders.order_details values(2200, 2, 1180, 5, 45.99);
Insert into a_bkorders.order_details values(2200, 3, 1128, 5, 46.20);
/* Sep 2011 */
Insert into a_bkorders.order_headers values(22909, '2011-09-25', 239427);
Insert into a_bkorders.order_details values(22909, 1, 1104, 5, 45.00);
Insert into a_bkorders.order_headers values(22910, '2011-09-25', 218709);
Insert into a_bkorders.order_details values(22910, 1, 1678, 5, 49.99);
Insert into a_bkorders.order_details values(22910, 2, 1162, 5, 35.00);
Insert into a_bkorders.order_headers values(32997, '2011-09-22', 239427);
Insert into a_bkorders.order_details values(32997, 1, 1948, 5, 40.94);
Insert into a_bkorders.order_details values(32997, 2, 1199, 5, 18.39);
Insert into a_bkorders.order_details values(32997, 3, 1457, 5, 53.99);
Insert into a_bkorders.order_details values(32997, 4, 1133, 5, 18.15);
Insert into a_bkorders.order_details values(32997, 5, 1894, 5, 36.79);
Insert into a_bkorders.order_headers values(32998, '2011-09-22', 261502);
Insert into a_bkorders.order_details values(32998, 1, 2006, 3, 20.00);
Insert into a_bkorders.order_headers values(41005, '2011-09-28', 290298);
Insert into a_bkorders.order_details values(41005, 1, 1142, 2, 42.45);
Insert into a_bkorders.order_details values(41005, 2, 1107, 4, 21.50);
Insert into a_bkorders.order_headers values(41006, '2011-09-28', 267780);
Insert into a_bkorders.order_details values(41006, 1, 1142, 10, 42.95);
Insert into a_bkorders.order_headers values(42899, '2011-09-29', 261502);
Insert into a_bkorders.order_details values(42899, 1, 1128, 5, 25.00);
Insert into a_bkorders.order_details values(42899, 2, 1103, 1 , 10.95);
/* Oct 2011 */
Insert into a_bkorders.order_headers values(21254, '2011-10-23', 263119);
Insert into a_bkorders.order_details values(21254, 2, 2008, 10, 46.95);
Insert into a_bkorders.order_details values(21254, 3, 2007, 10, 39.00);
Insert into a_bkorders.order_headers values(21255, '2011-10-28', 267780);
Insert into a_bkorders.order_details values(21255, 1, 1101, 5, 59.99);
Insert into a_bkorders.order_details values(21255, 2, 1142, 5, 39.00);
Insert into a_bkorders.order_details values(21255, 3, 1162, 2, 35.00);
Insert into a_bkorders.order_headers values(21261, '2011-10-28', 200368);
Insert into a_bkorders.order_details values(21261, 1, 1142, 100, 34.95);
Insert into a_bkorders.order_details values(21261, 2, 1128, 50, 46.95);
Insert into a_bkorders.order_details values(21261, 3, 2001, 100, 39.00);
Insert into a_bkorders.order_headers values(32905, '2011-10-02', 259906);
Insert into a_bkorders.order_details values(32905, 1, 2028, 1, 58.00);