学生信息管理系统建表和代码

建表语句：

CREATE TABLE student (
  id INT PRIMARY KEY AUTO_INCREMENT,
  name VARCHAR(50) NOT NULL,
  gender ENUM('男', '女') NOT NULL,
  age INT NOT NULL,
  major VARCHAR(50) NOT NULL,
  grade INT NOT NULL
);

代码示例：

import pymysql

# 连接数据库
conn = pymysql.connect(host='localhost', user='root', password='password', database='testdb', charset='utf8mb4')
cursor = conn.cursor()

# 添加学生信息
def add_student(name, gender, age, major, grade):
    sql = "INSERT INTO student (name, gender, age, major, grade) VALUES (%s, %s, %s, %s, %s)"
    cursor.execute(sql, (name, gender, age, major, grade))
    conn.commit()

# 查询学生信息
def query_student(name):
    sql = "SELECT * FROM student WHERE name = %s"
    cursor.execute(sql, name)
    result = cursor.fetchone()
    return result

# 修改学生信息
def update_student(name, major):
    sql = "UPDATE student SET major = %s WHERE name = %s"
    cursor.execute(sql, (major, name))
    conn.commit()

# 删除学生信息
def delete_student(name):
    sql = "DELETE FROM student WHERE name = %s"
    cursor.execute(sql, name)
    conn.commit()

# 关闭数据库连接
cursor.close()
conn.close()

注意：以上代码仅为示例，实际应用中需要考虑异常处理、数据验证等问题。