--1.编写程序计算1+2+...+100的和
--2.编写计算n!（n=20）的SQL语句，并显示计算结果
--3.使用系统函数：
--a.将身份证号的生日日期提取出来，例如19900913
--b.将你的手机号码中间第4至7位号码隐藏为****，138****9008.
--c.获取1-10之间的随机整数
--d.从你的身份证号获取年龄
--4.尝试求解所有的水仙花数。水仙花数是三位数，它的各位数的立方和等于这三位数本身。(--1. writes programs to compute the sum of 1+2+... +100
--2. writes the SQL statement for computing n! (n=20) and shows the results of the calculation
--3. uses the system function:
--a. extracts the birthday date of the ID number, such as 19900913
--b. hides fourth to 7 numbers in the middle of your phone number as * * *, 138****9008.
--c. gets the random integer between 1-10
--d. gets age from your ID card number
--4. tries to solve all the number of daffodils. The number of daffodils is three digits, and the number of cubic bits of the daffodils is equal to the three digits themselves.)