在划水的土拨鼠很有气魄

分类

/ 注册

全部文章（共49篇）

题解 | #【模板】栈#

#include <iostream> #include <stack> #include <string> using namespace std; int main() { int t, n, x; string s; stack&l...

2024-02-25

0 215

题解 | #将两个 SELECT 语句结合起来（二）#

SELECT * FROM OrderItems WHERE prod_id LIKE 'BNBG%' or quantity = 100 ORDER BY prod_id ASC

2024-02-16

0 174

题解 | #将两个 SELECT 语句结合起来（一）#

SELECT * FROM OrderItems WHERE quantity = 100 UNION SELECT * FROM OrderItems WHERE prod_id LIKE 'BNBG%' ORDER BY prod_id ASC # 愣是没懂“过滤数量为100的行”，笑死

2024-02-16

0 189

题解 | #列出供应商及其可供产品的数量#

SELECT v.vend_id, COUNT(prod_id) AS prod_id FROM Vendors v LEFT JOIN Products p ON v.vend_id = p.vend_id GROUP BY v.vend_id ORDER BY v.vend_id ASC # 产...

2024-02-16

0 177

题解 | #返回产品名称和每一项产品的总订单数#

SELECT prod_name, COUNT(order_num) AS orders FROM Products p LEFT JOIN OrderItems oi ON p.prod_id = oi.prod_id GROUP BY prod_name ORDER BY prod_name A...

2024-02-16

0 201

题解 | #确定最佳顾客的另一种方式（二）#

# GROUP BY 报错解决 # 添加cust_name # SQL 标准中不允许 SELECT 列表，HAVING 条件语句，或 ORDER BY 语句中出现 GROUP BY 中未列表的可聚合列。而 MySQL 中有一个状态 ONLY_FULL_GROUP_BY 来标识是否遵从这一标准，默认为...

2024-01-30

0 167

题解 | #确定哪些订单购买了 BR01 的产品（二）#

SELECT o.cust_id, order_date FROM Orders o WHERE o.order_num IN ( SELECT oi.order_num FROM OrderItems oi WHERE prod_id = 'BR01' ) ORDER BY...

2024-01-30

0 160

题解 | #返回顾客名称和相关订单号以及每个订单的总价#

SELECT cust_name, o.order_num, SUM(quantity*item_price) AS OrderTotal FROM Customers c INNER JOIN Orders o ON c.cust_id = o.cust_id INNER JOIN OrderIt...

2024-01-30

0 184

题解 | #返回每个顾客不同订单的总金额#

SELECT cust_id, ( SELECT SUM(item_price*quantity) FROM OrderItems oi WHERE oi.order_num = o.order_num GROUP BY oi.order_num ) AS total...

2024-01-29

0 188