QueryLight

This is a Beginner level article but can be referred readily by guys using Oracle Database moderately for a refernence. You can identify the duplicate records in Oracle Table by using a group by clause. You need to group by column / columns from which you are trying to identify the duplicates , use count() function to identify the duplicates : expression is self exploratory having count () > 1 . Ex 1 : Identify duplicates first names from employees table.  Note in this context : Employee records is not necessarily duplicate we are only trying to find employees with same first name. select empl_first_name , count(empl_first_name) from employees group by empl_first_name having count(empl_first_name) > 1 Ex 2 : Identify duplicates or repeats based on 2 or more columns. select empl_first_name , empl_last_name , count(empl_first_name) from employees group by empl_first_name , empl_last_name having count(1) > 1 Identify duplicate / repeats based on 2 or mo...