The Teachers' Day

博主来自越南,11月20日是越南教师节,学生们会用各种行动向老师表达感激。博主回忆高中一位老师,周五不上课,会讲世界历史故事、展示特别收藏和表演魔术,这种教学方式让大家既开心又能学习。
Hello everyone! I'm from Viet Nam, 20th nov is on coming, in my country thiis the Teaher's day, on this day we show our graitude to our teacher by many actions, I would love to hear your story about the teachers whom u love best, please tell me.

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During Teacher's Day we students usually do something special to our beloved teachers. We give them some gifts or we conduct some programs to cheer them up.

I remember this one teacher of mine in high school. Friday is considered our off day. He doesn't conduct his class lessons. What he usually do is that he tells us amazing stories related to world history, shows his unusual collections and performs some magic acts. All of us are looking forward to what is going to happen every Fridays.

With his style of teaching, we never get bored. We are having fun and we are also learning at the same time.
先展示下效果 https://pan.quark.cn/s/a4b39357ea24 遗传算法 - 简书 遗传算法的理论是根据达尔文进化论而设计出来的算法: 人类是朝着好的方向(最优解)进化,进化过程中,会自动选择优良基因,淘汰劣等基因。 遗传算法(英语:genetic algorithm (GA) )是计算数学中用于解决最佳化的搜索算法,是进化算法的一种。 进化算法最初是借鉴了进化生物学中的一些现象而发展起来的,这些现象包括遗传、突变、自然选择、杂交等。 搜索算法的共同特征为: 首先组成一组候选解 依据某些适应性条件测算这些候选解的适应度 根据适应度保留某些候选解,放弃其他候选解 对保留的候选解进行某些操作,生成新的候选解 遗传算法流程 遗传算法的一般步骤 my_fitness函数 评估每条染色体所对应个体的适应度 升序排列适应度评估值,选出 前 parent_number 个 个体作为 待选 parent 种群(适应度函数的值越小越好) 从 待选 parent 种群 中随机选择 2 个个体作为父方和母方。 抽取父母双方的染色体,进行交叉,产生 2 个子代。 (交叉概率) 对子代(parent + 生成的 child)的染色体进行变异。 (变异概率) 重复3,4,5步骤,直到新种群(parentnumber + childnumber)的产生。 循环以上步骤直至找到满意的解。 名词解释 交叉概率:两个个体进行交配的概率。 例如,交配概率为0.8,则80%的“夫妻”会生育后代。 变异概率:所有的基因中发生变异的占总体的比例。 GA函数 适应度函数 适应度函数由解决的问题决定。 举一个平方和的例子。 简单的平方和问题 求函数的最小值,其中每个变量的取值区间都是 [-1, ...
### SQL 计算每个学生从出生日期起的年龄 在不同数据库中计算年龄的方式略有不同,以下以 MySQL 和 SQL Server 为例: #### MySQL ```sql SELECT student_id, TIMESTAMPDIFF(YEAR, birth_date, CURDATE()) AS age FROM students; ``` #### SQL Server ```sql SELECT student_id, DATEDIFF(YEAR, birth_date, GETDATE()) - CASE WHEN MONTH(birth_date) > MONTH(GETDATE()) OR (MONTH(birth_date) = MONTH(GETDATE()) AND DAY(birth_date) > DAY(GETDATE())) THEN 1 ELSE 0 END AS age FROM students; ``` ### SQL 计算从今天到每个课程结束的天数 #### MySQL ```sql SELECT course_id, DATEDIFF(end_date, CURDATE()) AS remaining_days FROM courses; ``` #### SQL Server ```sql SELECT course_id, DATEDIFF(DAY, GETDATE(), end_date) AS remaining_days FROM courses; ``` ### SQL 提取所有学生的入学年份 #### MySQL ```sql SELECT student_id, YEAR(enrollment_date) AS enrollment_year FROM students; ``` #### SQL Server ```sql SELECT student_id, YEAR(enrollment_date) AS enrollment_year FROM students; ``` ### SQL 为课程开始日期增加 30 天用于迎新期 #### MySQL ```sql SELECT course_id, DATE_ADD(start_date, INTERVAL 30 DAY) AS new_start_date FROM courses; ``` #### SQL Server ```sql SELECT course_id, DATEADD(DAY, 30, start_date) AS new_start_date FROM courses; ``` ### SQL 查找所有课程开始日期是星期几 #### MySQL ```sql SELECT course_id, DAYNAME(start_date) AS day_of_week FROM courses; ``` #### SQL Server ```sql SELECT course_id, DATENAME(WEEKDAY, start_date) AS day_of_week FROM courses; ``` ### SQL 计算入学日期和今天之间的月差 #### MySQL ```sql SELECT student_id, TIMESTAMPDIFF(MONTH, enrollment_date, CURDATE()) AS month_difference FROM students; ``` #### SQL Server ```sql SELECT student_id, DATEDIFF(MONTH, enrollment_date, GETDATE()) AS month_difference FROM students; ``` ### SQL 将所有日期格式化为 'DD - MM - YYYY' #### MySQL ```sql SELECT student_id, DATE_FORMAT(birth_date, '%d - %m - %Y') AS formatted_birth_date FROM students; ``` #### SQL Server ```sql SELECT student_id, FORMAT(birth_date, 'dd - MM - yyyy') AS formatted_birth_date FROM students; ``` ### SQL 查找课程开始日期所在月的最后一天 #### MySQL ```sql SELECT course_id, LAST_DAY(start_date) AS last_day_of_month FROM courses; ``` #### SQL Server ```sql SELECT course_id, DATEADD(DAY, -1, DATEADD(MONTH, DATEDIFF(MONTH, 0, start_date) + 1, 0)) AS last_day_of_month FROM courses; ``` ### SQL 提取教师聘用日期所在的季度 #### MySQL ```sql SELECT teacher_id, QUARTER(hire_date) AS hire_quarter FROM teachers; ``` #### SQL Server ```sql SELECT teacher_id, DATEPART(QUARTER, hire_date) AS hire_quarter FROM teachers; ```
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