remove duplicate rows in sql

. Customer number, A. Company name from customer as a, customer as B WHERE A. Customer number >= B. Customer number GROUP by a. Customer number, B. Company name order by serial number; 2. SQL Server 2005 construct ordinal column Method One: SELECT RANK (DESC) as serial number, customer number, company name from customer; Method Two: With TABLE as (SELECT row_number () over (DESC) as ordinal number, customer number, company name from customer) SELE

Copy Code code as follows: Delete weibotopics where ID in (select MAX (Id) from Weibotopics GROUP by Weiboid,title has COUNT (*) > 1); SQL: Delete duplicate data, keep only one SQL statement, delete duplicates only one in thousands of records, there are some of the same records, how can you use SQL st

A few days ago, I read the article in the SQL section of SCID and explained how to quickly delete duplicate records in SQL Server. I browsed it. The author used four methods: creating temporary tables, using cursors, and using unique indexes. After a while, I found that the method I used was the easiest. Good stuff cannot be exclusive... The data in the test tabl

SQL Removal statement for duplicate recordsTable A:Id,nameTable B:Id,aid,value Select Case when A.name= ' CCC ' then null else A.name end name,b.value from Table A A, table B where a.id=b.aid Select Nullif (a.name, ' CCC ') name, b.value from table A, table B where a.id=b.aid Generate test data table: [TB] IF object_id (' [TB] ') is not NULLDROP TABLE [TB]GoCREATE TABLE [TB] ([name] [nv

SQL Single or group de-duplication Query methodThe following data are used for testing:Table Name: T_demo Id Name Project Grade 1 Xiao ming Mathematical 59 1 Xiao ming Chinese 59 1 Xiao ming English 59 2 Little Red Mathematical 100 2 Little Red Chinese 99 3 Smal

With SQL statements, delete duplicates and keep only one In thousands of records, there are some of the same records, how can you use SQL statements to delete duplicates? 1, look for redundant records in the table, duplicate records are based on a single field (Peopleid) to judge SELECT * from People where Peopleid in (select Peopleid from People GROUP by Peo

Label:Mesh: Zdjz_dis The NAME field has a duplicate value, delete the duplicate value deleted * from zdjz_dis WHERE name in (select Name from Zdjz_dis GROUP by NAME has count (NAME) >1); The above procedure will remove all the same values, including the one you want, and delete the delete * from Zdjz_dis WHERE ID in (select min (ID) from Zdjz_dis Group) as lon

. Customer No. group by a. Customer No., B. company name ORDER BY no;2. SQL Server 2005 constructs the sequence number column Method 1:Select rank () OVER (order by customer No. DESC) AS No., customer No., company name FROM customer;Method 2:WITH TABLE(SELECT ROW_NUMBER () OVER (order by customer No. DESC) AS No., customer No., company name FROM customer)SELECT * FROM TABLEWHERE no. BETWEEN 1 AND 3;3. rowid in Oracle can also be seen as the default id

Write a SQL query to delete all duplicate e-mail entries in a table named Person , keeping unique emails based on its smallest Id. +----+------------------+| Id | Email |+----+------------------+| 1 | [Email protected] | | 2 | [email protected] | | 3 | [Email protected] |+----+------------------+id is the primary key, column for this table.For example, after running your quer

I. Defining table Variables Copy Code code as follows: DECLARE @T1 Table ( UserID int, UserName nvarchar (50), CityName nvarchar (50) ); Copy Code code as follows: Insert into @T1 (userid,username,cityname) VALUES (1, ' A ', ' Shanghai ') Insert into @T1 (Userid,username,cityname) VALUES (2, ' B ', ' Beijing ') Insert into @T1 (Userid,username,cityname) VALUES (3, ' C ', ' Shanghai ') Insert into @T1 (userid,username,cityname) VALUES (4, '

One SQL statement is used to remove one MySQL retained. A few days ago, when I made a requirement, I needed to clear repeated records in mysql. The idea was to write them through code traversal, and then I thought it was too complicated, I thought that I should be able to solve the problem through an SQL statement. After checking the information, I have obtained

Wen/Xiachong Nightmare for Developers--delete duplicate recordsPresumably every developer has had a similar experience, and when querying or counting the database, the query and statistic results are inaccurate due to duplicate records in the table. The solution to this problem is to delete the duplicate records and keep only one of them.In

In thousands of records, there are some same records, how can you use SQL statements, delete duplicates1, look for redundant records in the table, duplicate records are based on a single field (Peopleid) to determineSELECT * from Peoplewhere Peopleid in (select Peopleid from People GROUP by Peopleid have count (Peopleid) > 1)2, delete redundant records in the table, dup