正则表达式：手机号码验证
使用 re.match() 严格匹配以 1 开头、第二位 3-9、后面 9 位数字的手机号（^1[3-9]\d{9}$），测试合法和非合法号码。
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import re
pattern = r"^1[3-9]\d{9}$"
result1 = re.match(pattern, "13812345678")
print(result1.group() if result1 else "匹配失败")
result2 = re.match(pattern, "23812345678")
print(result2.group() if result2 else "匹配失败")
✓ 正确
参考答案：import re
pattern = r"^1[3-9]\d{9}$"
result1 = re.match(pattern, "13812345678")
print(result1.group() if result1 else "匹配失败")
result2 = re.match(pattern, "23812345678")
print(result2.group() if result2 else "匹配失败")
正则表达式：提取邮箱信息
使用 re.search() 和分组从"我的工作邮箱是 admin@heima.com，请查收。"中提取用户名和域名。
查看参考答案 ▼
import re
text = "我的工作邮箱是 admin@heima.com，请查收。"</span>
pattern = r"([a-zA-Z0-9_]+)@([a-zA-Z0-9_]+\.[a-zA-Z0-9_]+)"
result = re.search(pattern, text)
if result:
print(f"完整邮箱: {result.group(0)}")
print(f"用户名: {result.group(1)}")
print(f"域名: {result.group(2)}")
✓ 正确
参考答案：import re
text = "我的工作邮箱是 admin@heima.com，请查收。"</span>
pattern = r"([a-zA-Z0-9_]+)@([a-zA-Z0-9_]+\.[a-zA-Z0-9_]+)"
result = re.search(pattern, text)
if result:
print(f"完整邮箱: {result.group(0)}")
print(f"用户名: {result.group(1)}")
print(f"域名: {result.group(2)}")
MySQL 基础：库与表的 DDL/DML 操作
创建 school_db 数据库和 students 表，包含 id、name、age 字段，完成 INSERT、UPDATE、DELETE 各一条。
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CREATE DATABASE IF NOT EXISTS school_db CHARSET=utf8;
USE school_db;
CREATE TABLE students(
id INT PRIMARY KEY,
name VARCHAR(50) NOT NULL,
age INT
);
INSERT INTO students(id, name, age) VALUES(1, "张三", 20);
UPDATE students SET age = 21 WHERE name = "张三";
DELETE FROM students WHERE age > 25;
✓ 正确
参考答案：CREATE DATABASE IF NOT EXISTS school_db CHARSET=utf8;
USE school_db;
CREATE TABLE students(
id INT PRIMARY KEY,
name VARCHAR(50) NOT NULL,
age INT
);
INSERT INTO students(id, name, age) VALUES(1, "张三", 20);
UPDATE students SET age = 21 WHERE name = "张三";
DELETE FROM students WHERE age > 25;
MySQL 查询：单表综合查询
基于 products 表（id, name, price, category_id）完成：价格>100查询、分组统计、排序取前3。
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SELECT name, price FROM products WHERE price > 100;
SELECT category_id, COUNT(*) FROM products GROUP BY category_id;
SELECT * FROM products ORDER BY price DESC LIMIT 0, 3;
✓ 正确
参考答案：SELECT name, price FROM products WHERE price > 100;
SELECT category_id, COUNT(*) FROM products GROUP BY category_id;
SELECT * FROM products ORDER BY price DESC LIMIT 0, 3;
MySQL 查询：多表关联查询
基于 users 和 orders 表，用 INNER JOIN 和 LEFT JOIN 查询用户订单。
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SELECT u.username, o.order_no
FROM users u
INNER JOIN orders o ON u.id = o.user_id;
SELECT u.username, o.order_no
FROM users u
LEFT JOIN orders o ON u.id = o.user_id;
✓ 正确
参考答案：SELECT u.username, o.order_no
FROM users u
INNER JOIN orders o ON u.id = o.user_id;
SELECT u.username, o.order_no
FROM users u
LEFT JOIN orders o ON u.id = o.user_id;