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...
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:/...
If you really want the data to be all in one table, you should try inserting all the rows from one table into the other. INSERT INTO table1 SELECT * FROM table2; To find rows in table2 which duplicate rows in table1: SELECT t2.id FROM table2 AS t2 JOIN table1 AS t1 ...
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。 DROP TABLE IF EXISTS contacts; CREATE TABLE contacts ( id INT PRIMAR...
在操作数据的时候，DataFrame对象中删除一个或多个列是常见的操作，并且实现方法较多，然而这中间有很多...
The rows returned are the duplicates and what I see returned are from table1. So I actually want to delete them from table2 if I understand this correctly, thus I should be returning table2 inmy SELECT, right? Then I could just delete those. Or am I over simplifying my position?
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) ...
DELETE a FROM wp.amalgamated_actors a INNER JOIN wp.amalgamated_actors a2 WHERE a.id < a2.id AND a.first_name = a2.first_name AND a.last_name = a2.last_name; 1 row(s) affected 0.093 sec 在這種情況下,受影響(已刪除)的列是id 是 12 的 NICK WAHLBERG。快速的 SELECT 語...
(0.00 sec) mysql> delete from for_delete; Query OK, 3 rows affected (0.04 sec) mysql> insert for_delete (name) values ('D'); Query OK, 1 row affected (0.02 sec) mysql> select * from for_delete; +---+---+ | id | name | +---+---+ | 4 | D | +---+---+ 1 row...
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 | +---+---+---+ | ...