remove duplicate rows in sql

In this example, we will use the following table, which has duplicate PK values. In this table, the primary key is two columns (col1 and col2 ). We cannot create a unique index or primary key constraint because the two rows have duplicate primary keys. This process demonstrates how to identify and delete duplicate prim

Tags: style blog color ar for SP data div on1 I. Defining table Variables2 3 DECLARE @T1 Table4 (5Useridint , 6UserNamenvarchar( -),7CityNamenvarchar( -)8 );9 Ten Insert into @T1(Userid,username,cityname)Values(1,'a','Shanghai') One Insert into @T1(Userid,username,cityname)Values(2,'b','Beijing') A Insert into @T1(Userid,username,cityname)Values(3,'C','Shanghai') - Insert into @T1(Userid,username,cityname)Values(4,'D','Beijing') - Insert into @T1(Userid,username,cityname)Values(5,'e','Shang

SQL: delete duplicate data. Only one record is retained. SQL2010-09-10 16:03:33 Read82 Comment0 Font Size:LargeMediumSmallSubscription There are some identical records in thousands of records. How can I use SQL statements to delete duplicates? 1. Search for redundant duplicate records in the Table.

the table, leaving only the record with ROWID minimumDelete from Vitae awhere (A.PEOPLEID,A.SEQ) in (select Peopleid,seq from Vitae GROUP by PEOPLEID,SEQ have count (*) > 1)and rowID not in (select min (rowid) from Vitae GROUP by PEOPLEID,SEQ have Count (*) >1)5. Find redundant duplicate records (multiple fields) in the table, not including the smallest ROWID recordsSELECT * FROM Vitae awhere (A.PEOPLEID,A.SEQ) in (select Peopleid,seq from Vitae GROU

Delete duplicate records and save the non-Repeated Records in table_name to # table_name Select distinct * into # table_name from table_nameDelete from table_nameSelect * into table_name from # table_nameDrop table # table_name This is related to the "select into" option, which can be in the database attributeIn the dialog box, check this item, or execute it in query analyzer.Execute sp_dboption 'db _ name', 'select into', 'true'Enable. The defa

Label:https://leetcode.com/problems/delete-duplicate-emails/Delete Duplicate EmailsWrite 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 p

Tags: http data sp DIV on C EF R BSWith SQL statements, delete duplicates only keep oneIn 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 Pe

Label:With SQL statements, delete duplicates only keep one 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

These are some useful SQL statements. For more information, see. These are some useful SQL statements. For more information, see. Delete duplicate records and save the non-Repeated Records in TABLE_NAME to # TABLE_NAME Select distinct * into # table_name from table_name Delete from table_name Select * into table_name from # table_name Drop table # table_name T

When the SQL statement deletes duplicate records and there is no size relationship between them, it processes repeated values. When the SQL statement deletes duplicate records and there is no size relationship between them, it processes repeated values. When the SQL state

Delete duplicate records Presumably 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 SQL Server,

Nightmare for Developers--delete duplicate records Presumably 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

SQL Multiple primary key tables, when the inserted data is duplicated, are prompted to violate the primary KEY constraint that cannot be inserted by the error. So, how do I find duplicate values for the inserted data? Workaround: Use Group bySuppose there is a table #a , there are saleid,vendorid,comid,price,saleprice,quantity and other fields. The primary key is: Saleid,vendorid,comid three of them. Assu

a. Customer No.> = B. 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

The table structure is created like the following code Copy Code code as follows: CREATE TABLE TEST_TB ( TestID int NOT null identity (1,1) primary key, Caption nvarchar (MB) null ); Go Solution 1: The first idea for this question may be: Is it OK to add a unique key to the caption field? OK, let's follow this thread and create a unique index first. Copy Code code as follows: CREATE UNIQUE nonclustered INDEX UN_TEST_TB On TEST_TB (Caption) Go

2601, Level 14, State 1, line 1thYou cannot insert a row of duplicate keys in an object ' DBO.TEST_TB ' with a unique index ' UN_TEST_TB '.The statement was terminated. So the solution is not going to work. Solution 2: Add a constraint so that SQL server, when inserting data, verifies that there is a value in the existing data that is now being inserted. Since this constraint is not a simple

Business requirementsRecently made a small tool for the company to bring data from one database (data source) into another (target database). The data required to import the target database cannot be duplicated. But the situation is that the data source itself has duplicate data. So you need to clear the data source data first.So we summarize the query and processing of the duplicate data. This is only a da