In this Tutorial we will see how to find duplicate rows in postgresql. Getting duplicate rows in postgresql table can be accomplished by using multiple methods each is explained with an example.
The table which we use for depiction is
Method 1: Find Duplicate Rows in Postgresql:
select distinct * from ExamScore where studentid in ( select studentid from ( select studentid, count(*) from ExamScore group by studentid HAVING count(*) > 1) as foo);
We have chosen duplicate row by counting the number of rows for each studentid and chosen the rows having count > 1.
Method 2: Find Duplicate Rows in Postgresql with partition by
We have chosen duplicate row by partition by and order by as shown below
select distinct * from ExamScore where studentid in ( select studentid from ( select studentid, ROW_NUMBER() OVER(PARTITION BY studentid ORDER BY studentid asc) AS Row FROM ExamScore ) as foo where foo.Row > 1);