牛客网SQL训练3—SQL必知必会

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一、检索数据

【题目1：从 Customers 表中检索所有的 ID】

select cust_id from Customers;

【题目2：检索并列出已订购产品的清单】

select 
	prod_id 
from OrderItems
group by prod_id
;

【题目3：检索所有列】

select * from Customers;

二、排序检索数据

【题目1：检索顾客名称并且排序】

select 
	cust_name 
from Customers
order by cust_name desc
;

【题目2：对顾客ID和日期排序】

select 
	cust_id
	,order_num
from Orders
order by cust_id asc,order_date desc
;

【题目3：按照数量和价格排序】

select
	quantity
	,item_price
from OrderItems
order by quantity desc,item_price desc
;

【题目4：检查SQL语句】

#-- 修改前
SELECT vend_name, 
FROM Vendors 
ORDER vend_name DESC;

#-- 修改后
SELECT vend_name
FROM Vendors 
ORDER BY vend_name DESC;

三、过滤数据

【题目1：返回固定价格的产品】

select 
	prod_id
	,prod_name
from Products
where prod_price='9.49'
;

【题目2：返回更高价格的产品】

select 
	prod_id
	,prod_name
from Products
where prod_price>='9'
;

【题目3：返回产品并且按照价格排序】

select 
	prod_name
	,prod_price
from Products
where prod_price between '3' and '6'
order by prod_price
;

【题目4：返回更多的产品】

select 
	order_num
from OrderItems
group by order_num 
having sum(quantity)>=100
;

四、高级数据过滤

【题目1：检索供应商名称】

select 
	vend_name
from Vendors
where vend_country='USA' and vend_state='CA'
;

【题目2：检索并列出已订购产品的清单】

select 
	order_num
	,prod_id
	,quantity
from OrderItems
where prod_id in ('BR01','BR02','BR03')
and quantity>100
;

【题目3：返回所有价格在 3美元到 6美元之间的产品的名称和价格】

select
	prod_name
	,prod_price
from Products
where prod_price between 3 and 6
order by prod_price
;

【题目4：纠错2】

#-- 修改前
SELECT vend_name 
FROM Vendors 
ORDER BY vend_name 
WHERE vend_country = 'USA' AND vend_state = 'CA';

#-- 修改后
SELECT vend_name 
FROM Vendors 
WHERE vend_country = 'USA' AND vend_state = 'CA'
ORDER BY vend_name;

五、用通配符进行过滤

【题目1：检索产品名称和描述 (一)】

select 
	prod_name
	,prod_desc
from Products
where prod_desc like '%toy%'
;

【题目2：检索产品名称和描述(二)】

select 
	prod_name
	,prod_desc
from Products
where prod_desc not like '%toy%'
order by prod_name
;

【题目3：检索产品名称和描述(三)】

select 
	prod_name
	,prod_desc
from Products
where prod_desc like '%toy%' and prod_desc like '%carrots%' 
;

【题目4：检索产品名称和描述 (四)】

select 
	prod_name
	,prod_desc
from Products
where prod_desc like '%toy%carrots%'  
;

六、创建计算字段

【题目1：别名】

select 
	vend_id
	,vend_name 		vname
	,vend_address  	vaddress	
	,vend_city      vcity
from Vendors
order by vend_name
;

【题目2：打折】

select 
	prod_id	
	,prod_price
	,prod_price*0.9 sale_price
from Products
;

七、使用函数处理数据

【题目1：顾客登录名】

select
	cust_id	
	,cust_name	
	,upper(concat(substr(cust_contact,1,2),substr(cust_city,1,3))) user_login
from Customers
;

【题目2：返回2020年1月的所有订单的订单号和订单日期】

select
	order_num	
	,order_date
from Orders
where substr(order_date,1,7)='2020-01'
order by order_date
;

八、汇总数据

【题目1：确定已售出产品的总数】

select 
	sum(quantity) items_ordered
from OrderItems
;

【题目2：确定已售出产品项 BRO1 的总数】

select 
	sum(quantity) items_ordered
from OrderItems
where prod_id='BR01'
;

【题目3：确定Products表中价格不超过10美元的最贵产品的价格】

select 
	max(prod_price) max_price
from Products
where prod_price<=10
;

九、分组数据

【题目1：返回每个订单号各有多少行数】

select 
	order_num
	,count(order_num) order_lines
from OrderItems
group by order_num
order by order_lines
;

【题目2：每个供应商成本最低的产品】

select
	vend_id
	,min(prod_price) cheapest_item
from Products
group by vend_id
order by cheapest_item
;

【题目3：确定最佳顾客】

select 
	order_num
from OrderItems
group by order_num
having sum(quantity)>=100
order by order_num
;

【题目4：确定最佳顾客的另一种方式 (一)】

select 
	order_num
	,sum(item_price*quantity) total_price
from OrderItems
group by order_num
having sum(item_price*quantity)>=1000
order by order_num
;

【题目5：纠错3】

#-- 修改前
SELECT order_num, COUNT(*) AS items 
FROM OrderItems 
GROUP BY items 
HAVING COUNT(*) >= 3 
ORDER BY items, order_num;

#-- 修改后
SELECT order_num, COUNT(*) AS items 
FROM OrderItems 
GROUP BY order_num 
HAVING COUNT(*) >= 3 
ORDER BY items, order_num;

十、使用子查询

【题目1：返回购买价格为10美元或以上产品的顾客列表】

select 
	cust_id
from Orders
where order_num in (
						select 
							order_num
						from OrderItems
						where item_price>=10
					)
;

【题目2：确定哪些订单购买了 prod id 为 BRO1 的产品 (一)】

select 
	cust_id	
	,order_date
from Orders
where order_num in (
						select 
							order_num
						from OrderItems
						where prod_id='BR01'
					)
order by order_date
;

【题目3：返回购买 prod id 为 BRO1 的产品的所有顾客的电子邮件 (一)】

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'
									    )
				  )
;

【题目4：返回每个顾客不同订单的总金额】

select 
	a.cust_id
	,sum(item_price*quantity) total_ordered
from Orders a 
left join OrderItems b 
on a.order_num=b.order_num
group by a.cust_id
order by total_ordered desc
;

【题目5：从 Products 表中检索所有的产品名称以及对应的销售总数】

select 
	prod_name	
	,sum(quantity) quant_sold
from Products a 
left join OrderItems b 
on a.prod_id=b.prod_id
group by prod_name
;

十一、联结表

【题目1：返回顾客名称和相关订单号】

select 
	cust_name	
	,order_num
from Customers a
join Orders b 
on a.cust_id=b.cust_id
order by cust_name,order_num
;

【题目2：返回顾客名称和相关订单号以及每个订单的总价】

select 
	cust_name	
	,b.order_num	
	,sum(quantity*item_price) OrderTotal
from Customers a 
join Orders b on a.cust_id=b.cust_id
join OrderItems c on b.order_num=c.order_num
group by cust_name,b.order_num	
order by cust_name,b.order_num
;

【题目3：确定哪些订单购买了 prod id 为 BRO1 的产品 (二)】

select
	cust_id	
	,order_date
from Orders
where order_num in (
						select 
							order_num
						from OrderItems
						where prod_id='BR01'
					)
order by order_date
;

【题目4：返回购买 prod id 为 BRO1 的产品的所有顾客的电子邮件 (二)】

select 
	cust_email
from OrderItems a
join Orders b on a.order_num=b.order_num
join Customers c on b.cust_id=c.cust_id
where a.prod_id='BR01'
;

【题目5：确定最佳顾客的另一种方式 (二)】

select 
	cust_name
	,sum(item_price*quantity) total_price
from Customers a 
join Orders b on a.cust_id=b.cust_id
join OrderItems c on b.order_num=c.order_num
group by cust_name
having sum(item_price*quantity)>1000
order by total_price
;

十二、创建高级联结

【题目1：检索每个顾客的名称和所有的订单号 (一)】

select 
	cust_name	
	,order_num
from Orders a 
join Customers b on a.cust_id=b.cust_id
order by cust_name
;

【题目2：检索每个顾客的名称和所有的订单号 (二)】

select 
	cust_name	
	,order_num
from Customers a 
left join Orders b on a.cust_id=b.cust_id
order by cust_name
;

【题目3：返回产品名称和与之相关的订单号】

select 
	prod_name	
	,order_num
from Products a 
left join OrderItems b on a.prod_id=b.prod_id
order by prod_name
;

【题目4：返回产品名称和每一项产品的总订单数】

select 
	prod_name	
	,count(order_num) order_num
from Products a 
left join OrderItems b on a.prod_id=b.prod_id
group by prod_name
order by prod_name
;

【题目5：列出供应商及其可供产品的数量】

select 
	a.vend_id	
	,count(prod_id) prod_id
from Vendors a 
left join Products b on a.vend_id=b.vend_id
group by a.vend_id
order by a.vend_id
;

十三、组合查询

【题目1：将两个 SELECT 语结合起来 (一)】

select 
	prod_id	
	,quantity
from OrderItems
where quantity=100
union all
select 
	prod_id	
	,quantity
from OrderItems
where prod_id like 'BNBG%'
order by prod_id
;

【题目2：将两个 SELECT 语结合起来 (二)】

select 
	prod_id	
	,quantity
from OrderItems
where quantity=100 or prod_id like 'BNBG%'
;

【题目3：组合 Products 表中的产品名称和 Customers 表中的顾客名称】

select 
	prod_name prod_name
from Products
union all
select 
	cust_name prod_name
from Customers
order by prod_name
;

【题目4：纠错4】

#-- 修改前
SELECT cust_name, cust_contact, cust_email 
FROM Customers 
WHERE cust_state = 'MI' 
ORDER BY cust_name; 
UNION 
SELECT cust_name, cust_contact, cust_email 
FROM Customers 
WHERE cust_state = 'IL'ORDER BY cust_name;

#-- 修改后
SELECT cust_name, cust_contact, cust_email 
FROM Customers 
WHERE cust_state = 'MI' 
UNION 
SELECT cust_name, cust_contact, cust_email 
FROM Customers 
WHERE cust_state = 'IL'
ORDER BY cust_name;