2020年9月27日
sql查找重复数据 group by having
摘要： leetcode:找到名字重复的邮箱名 Write a SQL query to find all duplicate emails in a table named Person. + + + | Id | Email | + + + | 1 | a@b.com | | 2 | c@d.com | 阅读全文
posted @ 2020-09-27 13:24 菠菜猫 阅读(712) 评论(0) 推荐(0)
sql请列出学生数大于等于5的课程 distinct去重
摘要： leetcode: 题目：There is a table courses with columns: student and class Please list out all classes which have more than or equal to 5 students. For exa 阅读全文
posted @ 2020-09-27 12:55 菠菜猫 阅读(553) 评论(0) 推荐(0)
sql按条件给属性赋值case then
摘要： leetcode题目： 要求： Given a table salary, such as the one below, that has m=male and f=female values. Swap all f and m values (i.e., change all f values t 阅读全文
posted @ 2020-09-27 12:47 菠菜猫 阅读(991) 评论(0) 推荐(0)