晓月清松

当前操作系统 ：windows10运行mysql版本：5.6.15出现错误的情况是：运行java多线程，需要频繁读写数据库错误提示：.......................Data source rejected establishment of connection, message from server: "Too many connections"

错误提示：错误代码： 1064You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'issplit = '1' where term = '00'' at line 1

插入数据库语句:INSERT INTO tag(term) VALUES(?)错误提示  Duplicate entry '一份' for key 'term'原因是 term 设置了唯一性的索引，无法插入重复的term的值

去除term重复的记录：DELETE FROM tag  WHERE id IN (SELECT id FROM (SELECT  MAX(id) AS id,COUNT(term) AS COUNT FROM tag GROUP BY term HAVING COUNT >1 ORDER BY COUNT DESC) AS tab )

今天select * from 表名 where to_days(时间字段名) = to_days(now());昨天SELECT * FROM 表名 WHERE TO_DAYS( NOW( ) ) - TO_DAYS( 时间字段名) 7天SELECT * FROM 表名 where DATE_SUB(CURDATE(), INTERVAL 7 DAY)