Skip to main content

Delete duplicate record

Q - Delete duplicate data from a table.

A - First of all create a table -

 create table del_duplicate
 (
 id int ,
 name varchar (15),
 class varchar (15)
 )

insert records :

 insert into del_duplicate values ('1','Abhishek','IT')
 insert into del_duplicate values ('1','Abhishek','IT')
 insert into del_duplicate values ('2','Amit','Civil')
 insert into del_duplicate values ('2','Amit','Civil')

 Query for delete duplicate data -:

Method 1:

SELECT DISTINCT id,name,class
INTO    tempTable
FROM    del_duplicate
GO
TRUNCATE TABLE del_duplicate
DROP TABLE del_duplicate
exec sp_rename 'tempTable', 'del_duplicate'

Method 2:

      SET NOCOUNT ON
      SET ROWCOUNT 1
      WHILE 1 = 1
       BEGIN
       DELETE   FROM del_duplicate
      WHERE    id IN (SELECT  id
      FROM    del_duplicate
     GROUP BY id
     HAVING  COUNT(*) > 1)
     IF @@Rowcount = 0
     BREAK ;
     END
     SET ROWCOUNT 0

Comments

Post a Comment

Popular posts from this blog

Methods of Rank Rows in SQL Server: ROW_NUMBER(), RANK(), DENSE_RANK() and NTILE()

SQL Server provides us with a number of window functions that help us to perform calculations across a set of rows, without the need to repeat the calls to the database. Unlike the standard aggregate functions, the window functions will not group the rows into a single output row, they will return a single aggregated value for each row, keeping the separate identities for those rows. The Window term here is not related to the Microsoft Windows operating system, it describes the set of rows that the function will process. One of the most useful types of window functions is Ranking Window Functions that are used to rank specific field values and categorize them according to the rank of each row, resulting in a single aggregated value for each participated row. There are four ranking window functions supported in SQL Server;  ROW_NUMBER(),   RANK() ,  DENSE_RANK()  and  NTILE() . All these functions are used to calculate ROWID for the provided rows window in ...
Post a Comment
Read more
Q- What is DBCC command in SQL sever. A - DBCC  (Database consistency checker ) are used to check the consistency of the databases. The DBCC commands are most useful for performance and trouble shooting exercises. I have listed down and explained all the DBCC commands available in SQL Server 2005, with examples. These are four types: Maintenance Informational Validation Miscellaneous                Maintenance Commands Performs maintenance tasks on a database, index, or file group. Syntax: DBCC  CLEANTABLE ( ‘DatabaseName’,’TableName.ColumnName’ ,0) 2.  DBREINDEX  – Builds one or more indexes for the table in the specified database. (Will be  removed  in the future version, use  ALTER INDEX  instead) Syntax: USE DatabaseName DBCC  DBREINDEX ( ‘TableName.ColumnName’,’PK_ID’ ,80) 3.  DROPCLEANBUFFERS  – Removes all clean buffers from buffer pool. Synta...
1 comment
Read more

Write a query that prints a list of employee names for employees in Employee having a salary greater than 2000

  Write a query that prints a list of employee names (i.e.: the  name  attribute) for employees in  Employee  having a salary greater than  2000  per month who have been employees for less than  10  months. Sort your result by ascending  employee_id . Input Format The  Employee  table containing employee data for a company is described as follows: Column Type employee_id Integer name String months Integer salary Integer where  employee_id  is an employee’s ID number,  name  is their name,  months  is the total number of months they’ve been working for the company, and  salary  is the their monthly salary. Sample Input employee_id name months salary 12228 Rose 15 1968 33645 Angela 1 3443 45692 Frank 17 1608 56118 Patrick 7 1345 59725 Lisa 11 2330 74197 Kimberly 16 4372 78454 Bonnie 8 1771 83565 Michael 6 2017 98607 Todd 5 3396 99989 Joe 9 3573 Sample Output Angela Michael Todd Joe Explanat...
1 comment
Read more