delete duplicate rows in sql

After learning about SQL for a while, I found a lot of duplicate records in the table I built to test (not indexed). Later, we summarize some ways to delete duplicate records, in Oracle, you can delete duplicate records through th

Test data preparationGive Test_user access to the Scott User EMP table Grant Select on to Test_user;Use Test_user to create an EMP table based on the Scott User's EMP table Create Table as Select * from Scott.emp;Insert the same data again Insert into Select * from EMP;Querying Current data Select * from Order by ASC;You can see that each record appears twice.Delete duplicate records1, delete redund

Let's now look at how to delete these records in SQL SERVER 2008, first of all, to simulate making some simple duplicate records: Copy Code code as follows: Create Table dbo. Employee ( [Id] int Primary KEY, [Name] varchar (50), [Age] int, [Sex] Bit default 1 ) Insert into Employee ([Id], [Name], [age], [Sex]) Values (1, ' James ', 25,default)

The code is as follows Copy Code Select A.*From temp a INNER join (select Name,sex to Temp GROUP by Name,sex has count (*) >1) bOn a.name = b.name and a.sex = B.sex To see a delete duplicate record instance User table structureCREATE TABLE User (varchar (uname) notnull;varchar (upass);); The code is as follows Copy Code Create a temporary table and cop

Let's take a look at how you can use it to delete duplicate records in a table: Copy Code code as follows: If Exists (Select * FROM Tempdb.Information_Schema.Tables Where table_name like ' #Temp% ') Drop Table #temp Create Table #temp ([Id] int, [Name] varchar, [age] int, [SEX] bit default 1) Go Insert into #temp ([Id], [Name], [age], [Sex]) Values (1, ' James ', 25,default) Insert into #t

unique across the database, ROWID determines which data files, blocks, and rows are in Oracle for each record. In duplicate records, all columns may have the same content, but ROWID will not be the same. The SQL statement is as follows: Delete from tbl where rowID in (select A.rowid From TBL A, tbl B where A.rowid>b.

You have a try1 I want to abroad1 Those are good Men1 We are good MenThe content after the 2nd character of each line is not checked, so I am tank root I love tank is the same. Delete a row in a large data file where some fields are duplicated A recently written data acquisition program generated a file containing more than 10 million rows of data, the data consists of 4 fields, according to the requirem

Searching and deleting duplicate rows in the database Search for records with all repeated titles:Select *From t_infoWhere (select count (*)From t_infoWhere title = A. Title)> 1)Order by title DESCI. Searching duplicate records1. Search for all Repeated RecordsSelect * from table where repeated field in (select repeated field from Table group by repeated

Someone in the group asked a question today. I have a table named test, which contains three fields A, B, and C. Now field B has a lot of duplicate data. Some of these duplicate data fields are empty, some have data, and the C field is correct. Excuse me: I want to remove duplicates Based on the B field. If the two data fields are the same, and the field is empty, if there is data in the other field,

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 ta

One, query a field repeat Copy Code code as follows: SELECT * From User u where U.user_name in (select U.user_name From User u GROUP BY U.user_name has count (*) > 1) Two, delete the duplicate of a few fields in the table Example: There are six records in the table. Where John and Harry records are duplicated.TableA Copy Code code as follows: ID Customer Phon

Linux text processing tools are very rich and powerful, such as a file: Copy Code code as follows: Cat Log Www.jb51.net 192.168.1.1 Www.jb51.net 192.168.1.1 Www.jb51.net 192.168.1.2 Ffffffffffffffffff Ffffffffffffffffff Eeeeeeeeeeeeeeeeeeee Fffffffffffffffffff Eeeeeeeeeeeeeeeeeeee Eeeeeeeeeeeeeeeeeeee Gggggggggggggggggggg You can remove duplicate rows in the followin

DataTable removes duplicate rows and performs distinct based on a field. datatabledistinct There are many methods on the Internet, such as using view processing: // Remove the duplicate row DataView dv = table. defaultView; table = dv. toTable (true, new string [] {"name", "code"}); in this case, the table has only two rows