MySQL: 子查询：我怎样才能让它工作？
MySQL: Sub-queries: How can I make this work?
我有这个任务，我想我对说明的内容感到非常困惑，但我正在构建一个子查询。我确定我做了一些荒谬的事情，但我不确定如何解决它。有没有人真正理解这些说明？
说明：
- Use sub-queries to determine which artist had an item ordered in highest quantity on an order? First determine the highest quantity on
any order, then determine the item id that is associated with it, then
display the artist.
我目前拥有的：
SELECT
SUM(order_details.order_qty) as 'Order Quantity',
items.item_ID as 'Item ID',
artists.artist_name as 'Artist'
FROM orders
JOIN order_details on order_details.order_ID = orders.order_ID
JOIN items on items.item_ID = order_details.item_ID
JOIN artists on items.artist_id = artists.artist_id
WHERE SUM(order_details.order_qty) >
(SELECT --How can I set this So that the quantity is being compared...this is where I'm stuck.)
GROUP BY items.item_id DESC;
您如何决定使用子查询。它被用在条件从句中……但这是出于比较原因，是吗？
所有代码：
/*Drop Tables*/
DROP TABLE IF EXISTS customers;
DROP TABLE IF EXISTS orders;
DROP TABLE IF EXISTS order_details;
DROP TABLE IF EXISTS items;
DROP TABLE IF EXISTS artists;
DROP TABLE IF EXISTS employees;
/*Create Tables*/
CREATE TABLE customers
(
customer_id INT,
customer_first_name VARCHAR(20),
customer_last_name VARCHAR(20) NOT NULL,
customer_address VARCHAR(50) NOT NULL,
customer_city VARCHAR(20) NOT NULL,
customer_state CHAR(2) NOT NULL,
customer_zip CHAR(5) NOT NULL,
customer_phone CHAR(10) NOT NULL,
customer_fax CHAR(10),
CONSTRAINT customers_pk
PRIMARY KEY (customer_id)
);
CREATE TABLE artists
(
artist_id INT NOT NULL,
artist_name VARCHAR(30),
CONSTRAINT artist_pk
PRIMARY KEY (artist_id)
);
CREATE TABLE items
(
item_id INT NOT NULL,
title VARCHAR(50) NOT NULL,
artist_id INT NOT NULL,
unit_price DECIMAL(9,2) NOT NULL,
CONSTRAINT items_pk
PRIMARY KEY (item_id),
CONSTRAINT items_fk_artists
FOREIGN KEY (artist_id) REFERENCES artists (artist_id)
);
CREATE TABLE employees
(
employee_id INT NOT NULL,
last_name VARCHAR(20) NOT NULL,
first_name VARCHAR(20) NOT NULL,
manager_id INT,
CONSTRAINT employees_pk
PRIMARY KEY (employee_id),
CONSTRAINT emp_fk_mgr FOREIGN KEY (manager_id) REFERENCES employees(employee_id)
);
CREATE TABLE orders
(
order_id INT NOT NULL,
customer_id INT NOT NULL,
order_date DATE NOT NULL,
shipped_date DATE,
employee_id INT,
CONSTRAINT orders_pk
PRIMARY KEY (order_id),
CONSTRAINT orders_fk_customers
FOREIGN KEY (customer_id) REFERENCES customers (customer_id),
CONSTRAINT orders_fk_employees
FOREIGN KEY (employee_id) REFERENCES employees (employee_id)
);
CREATE TABLE order_details
(
order_id INT NOT NULL,
item_id INT NOT NULL,
order_qty INT NOT NULL,
CONSTRAINT order_details_pk
PRIMARY KEY (order_id, item_id),
CONSTRAINT order_details_fk_orders
FOREIGN KEY (order_id)
REFERENCES orders (order_id),
CONSTRAINT order_details_fk_items
FOREIGN KEY (item_id)
REFERENCES items (item_id)
);
/*Insert Statements*/
INSERT INTO customers VALUES
(1,'Korah','Blanca','1555 W Lane Ave','Columbus','OH','43221','6145554435','6145553928'),
(2,'Yash','Randall','11 E Rancho Madera Rd','Madison','WI','53707','2095551205','2095552262'),
(3,'Johnathon','Millerton','60 Madison Ave','New York','NY','10010','2125554800',NULL),
(4,'Mikayla','Davis','2021 K Street Nw','Washington','DC','20006','2025555561',NULL),
(5,'Kendall','Mayte','4775 E Miami River Rd','Cleves','OH','45002','5135553043',NULL),
(6,'Kaitlin','Hostlery','3250 Spring Grove Ave','Cincinnati','OH','45225','8005551957','8005552826'),
(7,'Derek','Chaddick','9022 E Merchant Wy','Fairfield','IA','52556','5155556130',NULL),
(8,'Deborah','Davis','415 E Olive Ave','Fresno','CA','93728','5595558060',NULL),
(9,'Karina','Lacy','882 W Easton Wy','Los Angeles','CA','90084','8005557000',NULL),
(10,'Kurt','Nickalus','28210N Avenue Stanford','Valencia','CA','91355','8055550584','055556689'),
(11,'Kelsey','Eulalia','7833 N Ridge Rd','Sacramento','CA','95887','2095557500','2095551302'),
(12,'Anders','Rohansen','12345 E 67th Ave NW','Takoma Park','MD','24512','3385556772',NULL),
(13,'Thalia','Neftaly','2508 W Shaw Ave','Fresno','CA','93711','5595556245',NULL),
(14,'Gonzalo','Keeton','12 Daniel Road','Fairfield','NJ','07004','2015559742',NULL),
(15,'Ania','Irvin','1099 N Farcourt St','Orange','CA','92807','7145559000',NULL),
(16,'Dakota','Baylee','1033 NSycamore Ave.','Los Angeles','CA','90038','2135554322',NULL),
(17,'Samuel','Jacobsen','3433 E Widget Ave','Palo Alto','CA','92711','4155553434',NULL),
(18,'Justin','Javen','828 S Broadway','Tarrytown','NY','10591','8005550037',NULL),
(19,'Kyle','Marissa','789 E Mercy Ave','Phoenix','AZ','85038','9475553900',NULL),
(20,'Erick','Kaleigh','Five Lakepointe Plaza, Ste 500','Charlotte','NC','28217','7045553500',NULL),
(21,'Marvin','Quintin','2677 Industrial Circle Dr','Columbus','OH','43260','6145558600','6145557580'),
(22,'Rashad','Holbrooke','3467 W Shaw Ave #103','Fresno','CA','93711','5595558625','5595558495'),
(23,'Trisha','Anum','627 Aviation Way','Manhatttan Beach','CA','90266','3105552732',NULL),
(24,'Julian','Carson','372 San Quentin','San Francisco','CA','94161','6175550700',NULL),
(25,'Kirsten','Story','2401 Wisconsin Ave NW','Washington','DC','20559','2065559115',NULL);
INSERT INTO artists(artist_id,artist_name) VALUES
(10,'Umani'),
(11,'The Ubernerds'),
(12,'No Rest For The Weary'),
(13,'Burt Ruggles'),
(14,'Sewed the Vest Pocket'),
(15,'Jess & Odie'),
(16,'Onn & Onn');
INSERT INTO items (item_id,title,artist_id,unit_price) VALUES
(1,'Umami In Concert',10,17.95),
(2,'Race Car Sounds',11,13),
(3,'No Rest For The Weary',12,16.95),
(4,'More Songs About Structures and Comestibles',12,17.95),
(5,'On The Road With Burt Ruggles',13,17.5),
(6,'No Fixed Address',14,16.95),
(7,'Rude Noises',15,13),
(8,'Burt Ruggles: An Intimate Portrait',13,17.95),
(9,'Zone Out With Umami',10,16.95),
(10,'Etcetera',16,17);
INSERT INTO employees VALUES
(1,'Smith','Cindy',null),
(2,'Jones','Elmer',1),
(3,'Simonian','Ralph',2),
(9,'Locario','Paulo',1),
(8,'Leary','Rhea',9),
(4,'Hernandez','Olivia',9),
(5,'Aaronsen','Robert',4),
(6,'Watson','Denise',8),
(7,'Hardy','Thomas',2);
INSERT INTO orders VALUES
(19,1,'2012-10-23','2012-10-28',6),
(29,8,'2012-11-05','2012-11-11',6),
(32,11,'2012-11-10','2012-11-13',NULL),
(45,2,'2012-11-25','2012-11-30',NULL),
(70,10,'2012-12-28','2013-01-07',5),
(89,22,'2013-01-20','2013-01-22',7),
(97,20,'2013-01-29','2013-02-02',5),
(118,3,'2013-02-24','2013-02-28',7),
(144,17,'2013-03-21','2013-03-29',NULL),
(158,9,'2013-04-04','2013-04-20',NULL),
(165,14,'2013-04-11','2013-04-13',NULL),
(180,24,'2013-04-25','2013-05-30',NULL),
(231,15,'2013-06-14','2013-06-22',NULL),
(242,23,'2013-06-24','2013-07-06',3),
(264,9,'2013-07-15','2013-07-18',6),
(298,18,'2013-08-18','2013-09-22',3),
(321,2,'2013-09-09','2013-10-05',6),
(381,7,'2013-11-08','2013-11-16',7),
(413,17,'2013-12-05','2014-01-11',7),
(442,5,'2013-12-28','2014-01-03',5),
(479,1,'2014-01-30','2014-03-03',3),
(491,16,'2014-02-08','2014-02-14',5),
(523,3,'2014-03-07','2014-03-15',3),
(548,2,'2014-03-22','2014-04-18',NULL),
(550,17,'2014-03-23','2014-04-03',NULL),
(601,16,'2014-04-21','2014-04-27',NULL),
(607,20,'2014-04-25','2014-05-04',NULL),
(624,2,'2014-05-04','2014-05-09',NULL),
(627,17,'2014-05-05','2014-05-10',NULL),
(630,20,'2014-05-08','2014-05-18',7),
(651,12,'2014-05-19','2014-06-02',7),
(658,12,'2014-05-23','2014-06-02',7),
(687,17,'2014-06-05','2014-06-08',NULL),
(693,9,'2014-06-07','2014-06-19',NULL),
(703,19,'2014-06-12','2014-06-19',7),
(778,13,'2014-07-12','2014-07-21',7),
(796,17,'2014-07-19','2014-07-26',5),
(800,19,'2014-07-21','2014-07-28',NULL),
(802,2,'2014-07-21','2014-07-31',NULL),
(824,1,'2014-08-01',NULL,NULL),
(827,18,'2014-08-02',NULL,NULL),
(829,9,'2014-08-02',NULL,NULL);
INSERT INTO order_details VALUES
(381,1,1),
(601,9,1),
(442,1,1),
(523,9,1),
(630,5,1),
(778,1,1),
(693,10,1),
(118,1,1),
(264,7,1),
(607,10,1),
(624,7,1),
(658,1,1),
(800,5,1),
(158,3,1),
(321,10,1),
(687,6,1),
(827,6,1),
(144,3,1),
(479,1,2),
(630,6,2),
(796,5,1),
(97,4,1),
(601,5,1),
(800,1,1),
(29,10,1),
(70,1,1),
(165,4,1),
(180,4,1),
(231,10,1),
(413,10,1),
(491,6,1),
(607,3,1),
(651,3,1),
(703,4,1),
(802,3,1),
(824,7,2),
(829,1,1),
(550,4,1),
(796,7,1),
(693,6,1),
(29,3,1),
(32,7,1),
(242,1,1),
(298,1,1),
(479,4,1),
(548,9,1),
(627,9,1),
(778,3,1),
(19,5,1),
(89,4,1),
(242,6,1),
(264,4,1),
(550,1,1),
(693,7,3),
(824,3,1),
(829,5,1),
(829,9,1);
如果您看不懂文字，请告诉我。
好吧，让我们重做我的答案，首先这是我认为获得请求结果的最简单方法：
SELECT SUM(order_details.order_qty) as 'Order Quantity',
items.item_ID as 'Item ID',
artists.artist_name as 'Artist'
FROM order_details
JOIN items on items.item_ID = order_details.item_ID
JOIN artists on items.artist_id = artists.artist_id
GROUP BY order_details.item_ID
ORDER BY SUM(order_details.order_qty) DESC
# LIMIT 1
# You can uncomment the line above if you only want to return the artist with the highest selling item
使用子查询查询，根据我对说明的最佳解释：
SELECT artists.artist_name as 'Artist'
FROM artists
JOIN items on items.artist_id = artists.artist_id
WHERE items.item_id =(
SELECT order_details.item_ID as 'Item ID'
FROM order_details
GROUP BY order_details.item_id
ORDER BY SUM(order_details.order_qty) DESC
LIMIT 1);
在内部查询中，您 select item_id 在所有商品 ID 中的销售额最高。然后在外部查询中，您获取所有艺术家及其项目，并获取拥有等于内部查询结果的 item_id 的艺术家。
（编辑，我在第一次查询中使用错误的方式评论 MySQL，已修复）
我有这个任务，我想我对说明的内容感到非常困惑，但我正在构建一个子查询。我确定我做了一些荒谬的事情，但我不确定如何解决它。有没有人真正理解这些说明？
说明：
- Use sub-queries to determine which artist had an item ordered in highest quantity on an order? First determine the highest quantity on any order, then determine the item id that is associated with it, then display the artist.
我目前拥有的：
SELECT
SUM(order_details.order_qty) as 'Order Quantity',
items.item_ID as 'Item ID',
artists.artist_name as 'Artist'
FROM orders
JOIN order_details on order_details.order_ID = orders.order_ID
JOIN items on items.item_ID = order_details.item_ID
JOIN artists on items.artist_id = artists.artist_id
WHERE SUM(order_details.order_qty) >
(SELECT --How can I set this So that the quantity is being compared...this is where I'm stuck.)
GROUP BY items.item_id DESC;
您如何决定使用子查询。它被用在条件从句中……但这是出于比较原因，是吗？
所有代码：
/*Drop Tables*/
DROP TABLE IF EXISTS customers;
DROP TABLE IF EXISTS orders;
DROP TABLE IF EXISTS order_details;
DROP TABLE IF EXISTS items;
DROP TABLE IF EXISTS artists;
DROP TABLE IF EXISTS employees;
/*Create Tables*/
CREATE TABLE customers
(
customer_id INT,
customer_first_name VARCHAR(20),
customer_last_name VARCHAR(20) NOT NULL,
customer_address VARCHAR(50) NOT NULL,
customer_city VARCHAR(20) NOT NULL,
customer_state CHAR(2) NOT NULL,
customer_zip CHAR(5) NOT NULL,
customer_phone CHAR(10) NOT NULL,
customer_fax CHAR(10),
CONSTRAINT customers_pk
PRIMARY KEY (customer_id)
);
CREATE TABLE artists
(
artist_id INT NOT NULL,
artist_name VARCHAR(30),
CONSTRAINT artist_pk
PRIMARY KEY (artist_id)
);
CREATE TABLE items
(
item_id INT NOT NULL,
title VARCHAR(50) NOT NULL,
artist_id INT NOT NULL,
unit_price DECIMAL(9,2) NOT NULL,
CONSTRAINT items_pk
PRIMARY KEY (item_id),
CONSTRAINT items_fk_artists
FOREIGN KEY (artist_id) REFERENCES artists (artist_id)
);
CREATE TABLE employees
(
employee_id INT NOT NULL,
last_name VARCHAR(20) NOT NULL,
first_name VARCHAR(20) NOT NULL,
manager_id INT,
CONSTRAINT employees_pk
PRIMARY KEY (employee_id),
CONSTRAINT emp_fk_mgr FOREIGN KEY (manager_id) REFERENCES employees(employee_id)
);
CREATE TABLE orders
(
order_id INT NOT NULL,
customer_id INT NOT NULL,
order_date DATE NOT NULL,
shipped_date DATE,
employee_id INT,
CONSTRAINT orders_pk
PRIMARY KEY (order_id),
CONSTRAINT orders_fk_customers
FOREIGN KEY (customer_id) REFERENCES customers (customer_id),
CONSTRAINT orders_fk_employees
FOREIGN KEY (employee_id) REFERENCES employees (employee_id)
);
CREATE TABLE order_details
(
order_id INT NOT NULL,
item_id INT NOT NULL,
order_qty INT NOT NULL,
CONSTRAINT order_details_pk
PRIMARY KEY (order_id, item_id),
CONSTRAINT order_details_fk_orders
FOREIGN KEY (order_id)
REFERENCES orders (order_id),
CONSTRAINT order_details_fk_items
FOREIGN KEY (item_id)
REFERENCES items (item_id)
);
/*Insert Statements*/
INSERT INTO customers VALUES
(1,'Korah','Blanca','1555 W Lane Ave','Columbus','OH','43221','6145554435','6145553928'),
(2,'Yash','Randall','11 E Rancho Madera Rd','Madison','WI','53707','2095551205','2095552262'),
(3,'Johnathon','Millerton','60 Madison Ave','New York','NY','10010','2125554800',NULL),
(4,'Mikayla','Davis','2021 K Street Nw','Washington','DC','20006','2025555561',NULL),
(5,'Kendall','Mayte','4775 E Miami River Rd','Cleves','OH','45002','5135553043',NULL),
(6,'Kaitlin','Hostlery','3250 Spring Grove Ave','Cincinnati','OH','45225','8005551957','8005552826'),
(7,'Derek','Chaddick','9022 E Merchant Wy','Fairfield','IA','52556','5155556130',NULL),
(8,'Deborah','Davis','415 E Olive Ave','Fresno','CA','93728','5595558060',NULL),
(9,'Karina','Lacy','882 W Easton Wy','Los Angeles','CA','90084','8005557000',NULL),
(10,'Kurt','Nickalus','28210N Avenue Stanford','Valencia','CA','91355','8055550584','055556689'),
(11,'Kelsey','Eulalia','7833 N Ridge Rd','Sacramento','CA','95887','2095557500','2095551302'),
(12,'Anders','Rohansen','12345 E 67th Ave NW','Takoma Park','MD','24512','3385556772',NULL),
(13,'Thalia','Neftaly','2508 W Shaw Ave','Fresno','CA','93711','5595556245',NULL),
(14,'Gonzalo','Keeton','12 Daniel Road','Fairfield','NJ','07004','2015559742',NULL),
(15,'Ania','Irvin','1099 N Farcourt St','Orange','CA','92807','7145559000',NULL),
(16,'Dakota','Baylee','1033 NSycamore Ave.','Los Angeles','CA','90038','2135554322',NULL),
(17,'Samuel','Jacobsen','3433 E Widget Ave','Palo Alto','CA','92711','4155553434',NULL),
(18,'Justin','Javen','828 S Broadway','Tarrytown','NY','10591','8005550037',NULL),
(19,'Kyle','Marissa','789 E Mercy Ave','Phoenix','AZ','85038','9475553900',NULL),
(20,'Erick','Kaleigh','Five Lakepointe Plaza, Ste 500','Charlotte','NC','28217','7045553500',NULL),
(21,'Marvin','Quintin','2677 Industrial Circle Dr','Columbus','OH','43260','6145558600','6145557580'),
(22,'Rashad','Holbrooke','3467 W Shaw Ave #103','Fresno','CA','93711','5595558625','5595558495'),
(23,'Trisha','Anum','627 Aviation Way','Manhatttan Beach','CA','90266','3105552732',NULL),
(24,'Julian','Carson','372 San Quentin','San Francisco','CA','94161','6175550700',NULL),
(25,'Kirsten','Story','2401 Wisconsin Ave NW','Washington','DC','20559','2065559115',NULL);
INSERT INTO artists(artist_id,artist_name) VALUES
(10,'Umani'),
(11,'The Ubernerds'),
(12,'No Rest For The Weary'),
(13,'Burt Ruggles'),
(14,'Sewed the Vest Pocket'),
(15,'Jess & Odie'),
(16,'Onn & Onn');
INSERT INTO items (item_id,title,artist_id,unit_price) VALUES
(1,'Umami In Concert',10,17.95),
(2,'Race Car Sounds',11,13),
(3,'No Rest For The Weary',12,16.95),
(4,'More Songs About Structures and Comestibles',12,17.95),
(5,'On The Road With Burt Ruggles',13,17.5),
(6,'No Fixed Address',14,16.95),
(7,'Rude Noises',15,13),
(8,'Burt Ruggles: An Intimate Portrait',13,17.95),
(9,'Zone Out With Umami',10,16.95),
(10,'Etcetera',16,17);
INSERT INTO employees VALUES
(1,'Smith','Cindy',null),
(2,'Jones','Elmer',1),
(3,'Simonian','Ralph',2),
(9,'Locario','Paulo',1),
(8,'Leary','Rhea',9),
(4,'Hernandez','Olivia',9),
(5,'Aaronsen','Robert',4),
(6,'Watson','Denise',8),
(7,'Hardy','Thomas',2);
INSERT INTO orders VALUES
(19,1,'2012-10-23','2012-10-28',6),
(29,8,'2012-11-05','2012-11-11',6),
(32,11,'2012-11-10','2012-11-13',NULL),
(45,2,'2012-11-25','2012-11-30',NULL),
(70,10,'2012-12-28','2013-01-07',5),
(89,22,'2013-01-20','2013-01-22',7),
(97,20,'2013-01-29','2013-02-02',5),
(118,3,'2013-02-24','2013-02-28',7),
(144,17,'2013-03-21','2013-03-29',NULL),
(158,9,'2013-04-04','2013-04-20',NULL),
(165,14,'2013-04-11','2013-04-13',NULL),
(180,24,'2013-04-25','2013-05-30',NULL),
(231,15,'2013-06-14','2013-06-22',NULL),
(242,23,'2013-06-24','2013-07-06',3),
(264,9,'2013-07-15','2013-07-18',6),
(298,18,'2013-08-18','2013-09-22',3),
(321,2,'2013-09-09','2013-10-05',6),
(381,7,'2013-11-08','2013-11-16',7),
(413,17,'2013-12-05','2014-01-11',7),
(442,5,'2013-12-28','2014-01-03',5),
(479,1,'2014-01-30','2014-03-03',3),
(491,16,'2014-02-08','2014-02-14',5),
(523,3,'2014-03-07','2014-03-15',3),
(548,2,'2014-03-22','2014-04-18',NULL),
(550,17,'2014-03-23','2014-04-03',NULL),
(601,16,'2014-04-21','2014-04-27',NULL),
(607,20,'2014-04-25','2014-05-04',NULL),
(624,2,'2014-05-04','2014-05-09',NULL),
(627,17,'2014-05-05','2014-05-10',NULL),
(630,20,'2014-05-08','2014-05-18',7),
(651,12,'2014-05-19','2014-06-02',7),
(658,12,'2014-05-23','2014-06-02',7),
(687,17,'2014-06-05','2014-06-08',NULL),
(693,9,'2014-06-07','2014-06-19',NULL),
(703,19,'2014-06-12','2014-06-19',7),
(778,13,'2014-07-12','2014-07-21',7),
(796,17,'2014-07-19','2014-07-26',5),
(800,19,'2014-07-21','2014-07-28',NULL),
(802,2,'2014-07-21','2014-07-31',NULL),
(824,1,'2014-08-01',NULL,NULL),
(827,18,'2014-08-02',NULL,NULL),
(829,9,'2014-08-02',NULL,NULL);
INSERT INTO order_details VALUES
(381,1,1),
(601,9,1),
(442,1,1),
(523,9,1),
(630,5,1),
(778,1,1),
(693,10,1),
(118,1,1),
(264,7,1),
(607,10,1),
(624,7,1),
(658,1,1),
(800,5,1),
(158,3,1),
(321,10,1),
(687,6,1),
(827,6,1),
(144,3,1),
(479,1,2),
(630,6,2),
(796,5,1),
(97,4,1),
(601,5,1),
(800,1,1),
(29,10,1),
(70,1,1),
(165,4,1),
(180,4,1),
(231,10,1),
(413,10,1),
(491,6,1),
(607,3,1),
(651,3,1),
(703,4,1),
(802,3,1),
(824,7,2),
(829,1,1),
(550,4,1),
(796,7,1),
(693,6,1),
(29,3,1),
(32,7,1),
(242,1,1),
(298,1,1),
(479,4,1),
(548,9,1),
(627,9,1),
(778,3,1),
(19,5,1),
(89,4,1),
(242,6,1),
(264,4,1),
(550,1,1),
(693,7,3),
(824,3,1),
(829,5,1),
(829,9,1);
如果您看不懂文字，请告诉我。
好吧，让我们重做我的答案，首先这是我认为获得请求结果的最简单方法：
SELECT SUM(order_details.order_qty) as 'Order Quantity',
items.item_ID as 'Item ID',
artists.artist_name as 'Artist'
FROM order_details
JOIN items on items.item_ID = order_details.item_ID
JOIN artists on items.artist_id = artists.artist_id
GROUP BY order_details.item_ID
ORDER BY SUM(order_details.order_qty) DESC
# LIMIT 1
# You can uncomment the line above if you only want to return the artist with the highest selling item
使用子查询查询，根据我对说明的最佳解释：
SELECT artists.artist_name as 'Artist'
FROM artists
JOIN items on items.artist_id = artists.artist_id
WHERE items.item_id =(
SELECT order_details.item_ID as 'Item ID'
FROM order_details
GROUP BY order_details.item_id
ORDER BY SUM(order_details.order_qty) DESC
LIMIT 1);
在内部查询中，您 select item_id 在所有商品 ID 中的销售额最高。然后在外部查询中，您获取所有艺术家及其项目，并获取拥有等于内部查询结果的 item_id 的艺术家。
（编辑，我在第一次查询中使用错误的方式评论 MySQL，已修复）