Delete from customers1 where custid in (select Custid from #Temp_customers1) Will the above query work? Not entirely, as by using the above query, we lost all the duplicate records!! Let us see the table again.
SQL 删除重复记录 问题描述你想删除一个表里的重复记录,考虑如下的表。create table dupes (id integer, name varchar(10)) insert into dupes values (1, 'NAPOLEON') insert into dupes values (2, 'DYNAMITE') insert into dupes values (3, 'DYNAMITE') insert into dupes values (4, 'SHE SELLS') ...
The WHERE clause of the outer query uses a > ANY condition to check for duplicates. It will delete any row that has a rowid greater than at least one other row. This ensures that all but one of the rows that match your conditions is met, therefore removing all duplicates. So, how doe...
How to Delete Duplicate Records in SQL Server Usually on daily basis we usually need to perform removing duplicate records from a table. This post can help you to understand “How to Delete Duplicate Records in SQL Server”. Here consider an example for removing duplicate records. IF EXISTS(SE...
ERROR 1062 (23000): Duplicate entry '2' for key 1 mysql> alter ignore table invoices add unique index (invoice_number); Query OK, 4 rows affected (0.03 sec) Records: 4 Duplicates: 1 Warnings: 0 mysql> select * from invoices;
**/mysql> alter table students add key idx_class_no(class_no);Query OK, 0 rows affected (0.01 sec)Records: 0 Duplicates: 0 Warnings: 0 2.2.6 修改表名 修改表名的语法为 代码语言:javascript代码运行次数0 运行 AI代码解释 ALTER TABLE table_name_old RENAMETO table_name_new; 例如: ...
Records:0Duplicates:0Warnings:0mysql> insert into orders3(order_num,cust_id,order_date) values(20010,10007,'2005-09-01 00:00:00');#insert第一种方式 Query OK,1row affected (0.00sec) mysql>select*from orders3;+---+---+---+ | order_num | order_date | cust_id | +---...
首先创建原数据表 CREATE TABLE duplicate_table (id int, name varchar(20)); Query OK, 0 rows affected (0.01 sec) 再插入测试数据 INSERT INTO duplicate_table VALUES (100, ‘aaa’), (100, ‘aaa’), (200, ‘bbb’), (200, ‘bbb’), (200, ‘bbb’), (300, ‘ccc’); Query ...
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。 EXPLAINSELECT*fromt_table_1wheretask_idin(selectidfromt_table_2whereuid=1)
Therefore, removing the unique constraints is not one of the five ways to handle or delete duplicate records in SQL. We have better options. 1. Using INSERT INTO SELECT DISTINCT The first option for how to identify SQL records in SQL is to use DISTINCT in your SELECT. To explore the case...