摘要: 1、一个表中单个列重复的值 SELECT id, firstName, lastName, email, COUNT(*) FROM contacts GROUP BY firstName HAVING COUNT(firstName) > 1; 结果是:其中count(*)是表示重复的次数。 2、 阅读全文
posted @ 2020-05-08 17:39 Yuezc 阅读(368) 评论(0) 推荐(0) 编辑