SQL

 

1. Fetch Duplicate Entries in a Table 

Create table tempusers

(

userid int primary key,

username varchar(30) not null,

email varchar(50));

insert into tempusers values

(1, 'Sumit', 'sumit@gmail.com'),

(2, 'Reshma', 'reshma@gmail.com'),

(3, 'Farhana', 'farhana@gmail.com'),

(4, 'Robin', 'robin@gmail.com'),

(5, 'Robin', 'robin@gmail.com');

select * from tempusers;

Result: 

Query - for finding duplicate entry:

select userid, username, email

from (

select *,

row_number() over (partition by username order by userid) as rn

from tempusers u) x

where x.rn <> 1;