网上写写题 提高下自己的能力. Mysql平时写的是真的很少,所以训练一下下. 1.查找重复的电子邮箱 https://leetcode-cn.com/problems/duplicate-emails/ 我的解法: select distinct(t1.Email) from Person t1,Person t2 where t1.Id != t2.Id and t1.Email = t2.Email; 官方题解: select email from Person group by emai
官网上给的样题很少,带(*)的为正确答案. OBJECTIVE: 1.5: Given a code example, determine if a method is correctly overriding or overloading another method, and identify legal return values (including covariant returns), for the method.1) Given:1. class SuperFoo {2. S