delete duplicate rows in sql

. We'll use the Common Table Expression (CTE) and put the ' self ' Join query in it.With duplicates as (select distinct A.custid as customer_id from Customers2 a join customers2 B on A.custid Let ' s check which rows got deleted.SELECT * from Customers2 goScenario 2.b:delete all duplicate records but keep the first original oneLet ' s first truncate the CUSTOMERS2 table and add the same

SQL Delete duplicate rows (all or distinct)/*Delete a duplicate row SELECT statement Use the all or distinct option to display all rows in the table that meet the criteria, or

Mysql complex SQL statements (query and delete duplicate rows), mysqlsql 1. Find duplicate rows SELECT * FROM blog_user_relation a WHERE (a.account_instance_id,a.follow_account_instance_id) IN (SELECT account_instance_id,follow_ac

by name, autoid Select * from # TMP where autoid in (select autoid from # tmp2) The last select gets the result set with no duplicate name and address (but an autoid field is added, and this column can be omitted in the select clause during actual writing). 3. Some key fields are repeated, the record has an ID. the first method can delete all repeated .. (only records with the smallest

Where has count (*) >1 GROUP BY Col1,col2,col3,col4 ) The field followed by the GROUP BY clause is the condition that you use to determine the repetition, such as only col1, so as long as the content of the Col1 field is the same as that of the record. 5. Copy Code code as follows: Select Identity (int,1,1) as id,* into #temp from tabel SELECT * from #temp where ID in ( Select Max (ID) from #emp where has count (*) >1 GROUP by col1,col2,col3 ...) 6.

to judge repetition. For example, if only col1 is used, if the content of col1 is the same, the record is the same. 5.Copy codeThe Code is as follows: select identity (int, 1, 1) as id, * into # temp from tabelSelect * from # temp where id in (Select max (id) from # emp where having count (*)> 1 group by col1, col2, col3 ...) 6.Copy codeThe Code is as follows: select distinct * into # temp from tablenameDelete tablenameGoInsert tablename select * from # temp SqlclubGoDrop table # temp The prece

1. If an ID field exists, it is a unique field.Copy codeThe Code is as follows:Delect table where id not in (Select max (id) from table group by col1, col2, col3...) The field followed by the group by clause is the condition for you to judge repetition. For example, if only col1 is used, if the content of col1 is the same, the record is the same.2. This can also be used to determine all fields.Copy codeThe Code is as follows:Select * into # aa from table group by id1, id2 ,....

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How to delete duplicate rows and duplicates in Excel2003 according to Delete duplicate rows 1. Position the cursor in the table, data-filter-Advanced filter. 2. Set the location where the filter results are placed

VS2005 has been encapsulated for the DataTable to repeat the method: Copy Code code as follows: Remove Duplicate rows DataView dv = table. DefaultView; Table = dv. ToTable (True, new string[] {"Name", "Code"}); At this point, the table has only two lines of name, code without duplicates, and if the ID value is required Table = dv. ToTable (True, new string[] {"id", "name", "Co

by Field 1, Field 2, Field 3 having COUNT (*) > 1) Where: Field 1, Field 2, Field 3 refers to the three fields that need to establish a unique constraint, selfid refers to one of the self-increment fields in tables table. 2. Delete duplicate records and keep only the Selfid minimum records, that is, the first inserted records:[SQL]View Plaincopy

Php deletes duplicate rows in a text file. Php: How to delete duplicate rows in a text file this article describes how to delete duplicate rows