http://stackoverflow.com/questions/3311903/remove-duplicate-rows-in-mysql http://stackoverflow.com/questions/4685173/delete-all-duplicate-rows-except-for-one-in-mysql http://stackoverflow.com/questions/14046355/how-do-i-delete-all-the-duplicate-records-in-a-mysql-table-without-temp-tables http:/...
参见:https://www.mysqltutorial.org/mysql-delete-duplicate-rows/ 概括:在这个教程中,你将会学到多种用在 MySQL 中的删除重复行的方法。 一、准备样本数据 为了便于演示,我们用下面的脚本创建了表 contacts,并向其中插入了一些样本数据。 DROPTABLEIFEXISTScontacts;CREATETABLEcontacts ( idINTPRIMARYKEY AUTO_INC...
0 rows affected (0.00 sec) ② mysql> set global max_user_connections =100; Query OK, 0 rows affected (0.00 sec) ③ mysql> set global mysqlx_max_connections =100; Query OK, 0 rows affected (0.00 sec) ### 重启mysql服务,释放部分链接 systemctl start...
二(A)、 使用 DELETE JOIN 语句删除重复行 MySQL 提供了 DELETE JOIN 语句,这个语句可以使你快速移除重复的行。 下面的语句删除了重复的行,并且保留了(重复行中)最大的 id。 DELETE t1 FROM contacts t1 INNER JOIN contacts t2 WHERE < AND t1.email = t2.email; 这个查询引用了两次 contacts 表,因此,它...
insert...on duplicate key update column=value[,column=value]... 代码语言:javascript 代码运行次数:0 运行 AI代码解释 mysql>insert studentsvalues(31,444,'狄仁杰',56789)->on duplicate key update id=30,sn=555,name='狄仁杰',qq=56789;QueryOK,2rowsaffected(0.00sec)mysql>insert studentsvalues(31,...
开始我们拿sql到数据库查询平台查库执行计划,无奈这个平台有bug,delete语句无法查看,所以我们改成select,“应该”是一样。这个“应该”加了双引号,导致我们走了一点弯路。 EXPLAIN SELECT * from t_table_1 where task_id in (select id from t_table_2 where uid = 1) ...
ERROR 1062 (23000): Duplicate entry 'u2@email.com' for key 'idx_email' 提示有重复数据,导致创建唯一索引失败。 3.看看我们插入的数据 select * from demo_table; 执行结果: +---+---+---+ | id | name | email | +---+---+---+ | ...
Last_Errno:1062Last_Error: CouldnotexecuteWrite_rows eventontabletest.t;Duplicateentry'4'forkey'PRIMARY',Error_code:1062;handlererror HA_ERR_FOUND_DUPP_KEY;the event's master log mysql-bin.000014,end_log_pos1505 1. 针对这个报错,我们首先要考虑是不是在从库中误操作导致的。结果发现,我们在从库...
Delete from table_name where (set conditions here) limit 1 The "limit 1" will prevent the query from going beyond this threshold of results to delete. You may want to backup the table in question before you go forward with this. http://forums.mysql.com/read.php?21,135990,...
rows in set (0.00 sec) ### ① 临时修改默认大小 mysql> set global max_allowed_packet = 16*1024*1024; Query OK, 0 rows affected (0.01 sec) --- 修改完之后需要退出重新进入mysql mysql> show VARIABLES like '%max_allowed_packet%'; +---+---+ | Variable_name | Value | +---+---+...