给我写个增删改查

以下是一个简单的增删改查操作示例：

class Student:
    def __init__(self, id, name, age):
        self.id = id
        self.name = name
        self.age = age

class StudentDatabase:
    def __init__(self):
        self.students = []

    def add_student(self, id, name, age):
        student = Student(id, name, age)
        self.students.append(student)

    def delete_student(self, id):
        for student in self.students:
            if student.id == id:
                self.students.remove(student)

    def update_student(self, id, name, age):
        for student in self.students:
            if student.id == id:
                student.name = name
                student.age = age

    def find_student(self, id):
        for student in self.students:
            if student.id == id:
                return student
        return None

# 使用示例
db = StudentDatabase()

# 添加学生
db.add_student(1, "张三", 18)
db.add_student(2, "李四", 19)
db.add_student(3, "王五", 20)

# 查询学生
student = db.find_student(2)
print(student.name) # 输出：李四

# 更新学生
db.update_student(2, "李四2", 20)
student = db.find_student(2)
print(student.name) # 输出：李四2

# 删除学生
db.delete_student(3)
student = db.find_student(3)
print(student) # 输出：None