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数据库系统原理与应用教程（065）—— MySQL 练习题：操作题 62-70（九）：分组查询与子查询

2022-07-30 17:26:00 【睿思达DBA_WGX】

数据库系统原理与应用教程（065）—— MySQL 练习题：操作题 62-70（九）：分组查询与子查询

62、分组查询（1）

数据表：OrderItems，表中数据如下：

order_num
a002
a002
a002
a004
a007

【问题】编写 SQL 语句，返回每个订单号（order_num）各有多少行数（order_lines），并按 order_lines 对结果进行升序排序。查询结果如下：

order_numorder_lines
a0041
a0071
a0023

表结构及数据如下：

/* DROP TABLE IF EXISTS `OrderItems`; CREATE TABLE IF NOT EXISTS `OrderItems`( order_num VARCHAR(255) NOT NULL COMMENT '商品订单号' ); INSERT `OrderItems` VALUES ('a002'),('a002'),('a002'),('a004'),('a007'); */

解答：

/* select order_num, count(*) order_lines from OrderItems group by order_num order by order_lines; */
mysql> select order_num, count(*) order_lines
    -> from OrderItems
    -> group by order_num order by order_lines;
+-----------+-------------+
| order_num | order_lines |
+-----------+-------------+
| a004      |           1 |
| a007      |           1 |
| a002      |           3 |
+-----------+-------------+
3 rows in set (0.00 sec)

63、分组查询（2）

有数据表：Products，表中数据如下：

vend_idprod_price
a0011100
a00190.1
b00191000
b00196980
b001920

【问题】编写 SQL 语句，返回名为 cheapest_item 的字段，该字段包含每个供应商成本最低的产品（使用 Products 表中的 prod_price），然后从最低成本到最高成本对结果进行升序排序。查询结果如下：

vend_idcheapest_item
a00190.1
b001920
a0011100

表结构及数据如下：

/* DROP TABLE IF EXISTS `Products`; CREATE TABLE IF NOT EXISTS `Products` ( `vend_id` VARCHAR(255) NOT NULL COMMENT '供应商ID', `prod_price` DOUBLE NOT NULL COMMENT '产品价格' ); INSERT INTO `Products` VALUES ('a0011',100), ('a0019',0.1), ('b0019',1000), ('b0019',6980), ('b0019',20); */

解答：

/* select vend_id, min(prod_price) cheapest_item from Products group by vend_id order by cheapest_item; */
mysql> select vend_id, min(prod_price) cheapest_item
    -> from Products
    -> group by vend_id
    -> order by cheapest_item;
+---------+---------------+
| vend_id | cheapest_item |
+---------+---------------+
| a0019   |           0.1 |
| b0019   |            20 |
| a0011   |           100 |
+---------+---------------+
3 rows in set (0.00 sec)

64、分组查询（3）

数据表：OrderItems，表中数据如下：

order_numquantity
a1105
a21100
a2200
a41121
a510
a219
a75

【问题】编写 SQL 语句，返回订单数量总和不小于 100 的所有订单号，最后结果按照订单号升序排序。查询结果如下：

order_num
a1
a2
a4

表结构及数据如下：

/* DROP TABLE IF EXISTS `OrderItems`; CREATE TABLE IF NOT EXISTS `OrderItems`( order_num VARCHAR(255) NOT NULL COMMENT '商品订单号', quantity INT(255) NOT NULL COMMENT '商品数量' ); INSERT `OrderItems` VALUES ('a1',105),('a2',200),('a4',1121),('a5',10),('a7',5); */

解答：

/* select order_num from OrderItems group by order_num having sum(quantity) >= 100 order by order_num; */
mysql> select order_num from OrderItems
    -> group by order_num having sum(quantity) >= 100
    -> order by order_num;
+-----------+
| order_num |
+-----------+
| a1        |
| a2        |
| a4        |
+-----------+
3 rows in set (0.00 sec)

65、分组查询（4）

数据表：OrderItems，表中数据如下：

order_numitem_pricequantity
a110105
a211100
a21200
a421121
a5510
a2119
a775

【问题】编写 SQL 语句，返回订单总价不小于 1000 的所有订单号，最后的结果按订单号进行升序排序（订单总价 = item_price * quantity）。查询结果如下：

order_numtotal_price
a11050
a21319
a42242

表结构及数据如下：

/* DROP TABLE IF EXISTS `OrderItems`; CREATE TABLE IF NOT EXISTS `OrderItems`( order_num VARCHAR(255) NOT NULL COMMENT '商品订单号', item_price INT(16) NOT NULL COMMENT '售出价格', quantity INT(16) NOT NULL COMMENT '商品数量' ); INSERT `OrderItems` VALUES ('a1',10,105),('a2',1,1100),('a2',1,200),('a4',2,1121),('a5',5,10),('a2',1,19),('a7',7,5); */

解答：

/* select order_num, sum(item_price * quantity) total_price from OrderItems group by order_num having total_price >= 1000 order by order_num; */
mysql> select order_num, sum(item_price * quantity) total_price 
    -> from OrderItems
    -> group by order_num having total_price >= 1000
    -> order by order_num;
+-----------+-------------+
| order_num | total_price |
+-----------+-------------+
| a1        |        1050 |
| a2        |        1319 |
| a4        |        2242 |
+-----------+-------------+
3 rows in set (0.01 sec)

66、子查询（1）

数据表：OrderItems，表中数据如下：

order_numitem_price
a110
a21
a21
a42
a55
a21
a77

数据表：Orders，表中数据如下：

order_numcust_id
a1cust10
a2cust1
a2cust1
a4cust2
a5cust5
a2cust1
a7cust7

【问题】使用子查询，查询购买价格为 10 元或以上产品的顾客列表。查询结果如下：

cust_id
cust10

表结构及数据如下：

/* DROP TABLE IF EXISTS `OrderItems`; DROP TABLE IF EXISTS `Orders`; CREATE TABLE IF NOT EXISTS `OrderItems`( order_num VARCHAR(255) NOT NULL COMMENT '商品订单号', item_price INT(16) NOT NULL COMMENT '售出价格' ); CREATE TABLE IF NOT EXISTS `Orders`( order_num VARCHAR(255) NOT NULL COMMENT '商品订单号', cust_id VARCHAR(255) NOT NULL COMMENT '顾客id' ); INSERT `OrderItems` VALUES ('a1',10),('a2',1),('a2',1),('a4',2),('a5',5),('a2',1),('a7',7); INSERT `Orders` VALUES ('a1','cust10'),('a2','cust1'),('a2','cust1'),('a4','cust2'),('a5','cust5'),('a2','cust1'),('a7','cust7'); */

解答：

/* select cust_id from Orders where order_num in (select order_num from OrderItems where item_price >= 10); */
mysql> select cust_id from Orders 
    -> where order_num in 
    -> (select order_num from OrderItems where item_price >= 10);
+---------+
| cust_id |
+---------+
| cust10  |
+---------+
1 row in set (0.00 sec)

67、子查询（2）

数据表：OrderItems，表中数据如下：

prod_idorder_num
BR01a0001
BR01a0002
BR02a0003
BR02a0013

数据表：Orders，表中数据如下：

order_numcust_idorder_date
a0001cust102022-01-01 00:00:00
a0002cust12022-01-01 00:01:00
a0003cust12022-01-02 00:00:00
a0013cust22022-01-01 00:20:00

【问题】编写 SQL 语句，查询哪些订单（在 OrderItems 中）购买了 prod_id 为 “BR01” 的产品，返回每个产品对应的顾客 ID（cust_id）和订单日期（order_date），按订购日期对结果进行升序排序。查询结果如下：

cust_idorder_date
cust102022-01-01 00:00:00
cust12022-01-01 00:01:00

表结构及数据如下：

/* DROP TABLE IF EXISTS `OrderItems`; DROP TABLE IF EXISTS `Orders`; CREATE TABLE IF NOT EXISTS `OrderItems`( prod_id VARCHAR(255) NOT NULL COMMENT '产品id', order_num VARCHAR(255) NOT NULL COMMENT '商品订单号' ); CREATE TABLE IF NOT EXISTS `Orders`( order_num VARCHAR(255) NOT NULL COMMENT '商品订单号', cust_id VARCHAR(255) NOT NULL COMMENT '顾客id', order_date TIMESTAMP NOT NULL COMMENT '下单时间' ); INSERT `OrderItems` VALUES ('BR01','a0001'),('BR01','a0002'),('BR02','a0003'),('BR02','a0013'); INSERT `Orders` VALUES ('a0001','cust10','2022-01-01 00:00:00'),('a0002','cust1','2022-01-01 00:01:00'),('a0003','cust1','2022-01-02 00:00:00'),('a0013','cust2','2022-01-01 00:20:00'); */

解答：

/* select cust_id, order_date from Orders where order_num in (select order_num from OrderItems where prod_id = 'BR01') order by order_date; */
mysql> select cust_id, order_date from Orders 
    -> where order_num in (select order_num from OrderItems where prod_id = 'BR01')
    -> order by order_date;
+---------+---------------------+
| cust_id | order_date          |
+---------+---------------------+
| cust10  | 2022-01-01 00:00:00 |
| cust1   | 2022-01-01 00:01:00 |
+---------+---------------------+
2 rows in set (0.00 sec)

68、子查询（3）

数据表：OrderItems，表中数据如下：

prod_idorder_num
BR01a0001
BR01a0002
BR02a0003
BR02a0013

数据表：Orders，表中数据如下：

order_numcust_idorder_date
a0001cust102022-01-01 00:00:00
a0002cust12022-01-01 00:01:00
a0003cust12022-01-02 00:00:00
a0013cust22022-01-01 00:20:00

数据表：Customers，表中数据如下：

cust_idcust_email
cust10[email protected]
cust1[email protected]
cust2[email protected]

【问题】查询购买 prod_id 为 BR01 的产品的所有顾客的电子邮件。查询结果如下：

cust_email
[email protected]
[email protected]

表结构及数据如下：

/* DROP TABLE IF EXISTS `OrderItems`; CREATE TABLE IF NOT EXISTS `OrderItems`( prod_id VARCHAR(255) NOT NULL COMMENT '产品id', order_num VARCHAR(255) NOT NULL COMMENT '商品订单号' ); INSERT `OrderItems` VALUES ('BR01','a0001'),('BR01','a0002'),('BR02','a0003'),('BR02','a0013'); DROP TABLE IF EXISTS `Orders`; CREATE TABLE IF NOT EXISTS `Orders`( order_num VARCHAR(255) NOT NULL COMMENT '商品订单号', cust_id VARCHAR(255) NOT NULL COMMENT '顾客id', order_date TIMESTAMP NOT NULL COMMENT '下单时间' ); INSERT `Orders` VALUES ('a0001','cust10','2022-01-01 00:00:00'),('a0002','cust1','2022-01-01 00:01:00'),('a0003','cust1','2022-01-02 00:00:00'),('a0013','cust2','2022-01-01 00:20:00'); DROP TABLE IF EXISTS `Customers`; CREATE TABLE IF NOT EXISTS `Customers`( cust_id VARCHAR(255) NOT NULL COMMENT '顾客id', cust_email VARCHAR(255) NOT NULL COMMENT '顾客email' ); INSERT `Customers` VALUES ('cust10','[email protected]'),('cust1','[email protected]'),('cust2','[email protected]'); */

解答：

/* select cust_email from Customers where cust_id in (select cust_id from Orders where order_num in (select order_num from OrderItems where prod_id = 'BR01') ); */
mysql> select cust_email from Customers where cust_id in
    ->     (select cust_id from Orders where order_num in 
    ->          (select order_num from OrderItems where prod_id = 'BR01')
    ->     );
+-----------------+
| cust_email      |
+-----------------+
| cust10@cust.com |
| cust1@cust.com  |
+-----------------+
2 rows in set (0.00 sec)

69、子查询（4）

数据表：OrderItems（订单信息），表中有订单号：order_num，商品售出价格：item_price，商品数量：quantity。表中的数据如下：

order_numitem_pricequantity
a000110105
a000211100
a00021200
a001321121
a0003510
a0003119
a000375

数据表：Orders（订单表），表中有订单号：order_num，客户号：cust_id，表中数据如下：

order_numcust_id
a0001cust10
a0002cust1
a0003cust1
a0013cust2

【问题】编写 SQL语句，查询顾客 ID（Orders 表中的 cust_id）以及每个顾客的订单总数（total_ordered），将结果按金额从大到小排序。查询结果如下：

cust_idtotal_ordered
cust22242
cust11404
cust101050

表结构及数据如下：

/* DROP TABLE IF EXISTS `OrderItems`; CREATE TABLE IF NOT EXISTS `OrderItems`( order_num VARCHAR(255) NOT NULL COMMENT '商品订单号', item_price INT(16) NOT NULL COMMENT '售出价格', quantity INT(16) NOT NULL COMMENT '商品数量' ); INSERT `OrderItems` VALUES ('a0001',10,105),('a0002',1,1100),('a0002',1,200),('a0013',2,1121),('a0003',5,10),('a0003',1,19),('a0003',7,5); DROP TABLE IF EXISTS `Orders`; CREATE TABLE IF NOT EXISTS `Orders`( order_num VARCHAR(255) NOT NULL COMMENT '商品订单号', cust_id VARCHAR(255) NOT NULL COMMENT '顾客id' ); INSERT `Orders` VALUES ('a0001','cust10'),('a0002', 'cust1'),('a0003','cust1'),('a0013','cust2'); */

解答：

/* select o.cust_id, sum(item_price * quantity) total_ordered from OrderItems oi join Orders o on oi.order_num = o.order_num group by o.cust_id order by total_ordered desc; */
mysql> select o.cust_id, sum(item_price * quantity) total_ordered
    -> from OrderItems oi join Orders o on oi.order_num = o.order_num
    -> group by o.cust_id
    -> order by total_ordered desc;
+---------+---------------+
| cust_id | total_ordered |
+---------+---------------+
| cust2   |          2242 |
| cust1   |          1404 |
| cust10  |          1050 |
+---------+---------------+
3 rows in set (0.00 sec)

70、子查询（5）

数据表：Products，包含产品名称：prod_name、产品 id：prod_id，表中数据如下：

prod_idprod_name
a0001egg
a0002sockets
a0013coffee
a0003cola

数据表：OrderItems（订单商品表），包含产品 id：prod_id、售出数量：quantity，表中数据如下：

prod_idquantity
a0001105
a00021100
a0002200
a00131121
a000310
a000319
a00035

【问题】

【问题】编写 SQL 语句，从 Products 表中检索所有的产品名称（prod_name），以及名为 quant_sold（产品售出数量总和）的计算列。查询结果如下：

prod_namequant_sold
egg105
sockets1300
coffee1121
cola34

表结构及数据如下：

/* DROP TABLE IF EXISTS `Products`; CREATE TABLE IF NOT EXISTS `Products` ( `prod_id` VARCHAR(255) NOT NULL COMMENT '产品 ID', `prod_name` VARCHAR(255) NOT NULL COMMENT '产品名称' ); INSERT INTO `Products` VALUES ('a0001','egg'), ('a0002','sockets'), ('a0013','coffee'), ('a0003','cola'); DROP TABLE IF EXISTS `OrderItems`; CREATE TABLE IF NOT EXISTS `OrderItems`( prod_id VARCHAR(255) NOT NULL COMMENT '产品id', quantity INT(16) NOT NULL COMMENT '商品数量' ); INSERT `OrderItems` VALUES ('a0001',105),('a0002',1100),('a0002',200),('a0013',1121),('a0003',10),('a0003',19),('a0003',5); */

解答：

/* select p.prod_name, sum(quantity) quant_sold from OrderItems o join Products p on o.prod_id = p.prod_id group by p.prod_name; */

mysql> select p.prod_name, sum(quantity) quant_sold
    -> from OrderItems o join Products p on o.prod_id = p.prod_id
    -> group by p.prod_name;
+-----------+------------+
| prod_name | quant_sold |
+-----------+------------+
| coffee    |       1121 |
| cola      |         34 |
| egg       |        105 |
| sockets   |       1300 |
+-----------+------------+
4 rows in set (0.00 sec)
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