SQL DELETE DUPLICATE ROWS

When dealing with large datasets, it’s common to encounter duplicate records in a table. Duplicate data can cause inaccurate record fetching results if it is not managed appropriately. To ensure accuracy, we must retrieve unique records instead of duplicates.

To solve this issue, SQL provides the DISTINCT keyword, which is used with the SELECT statement to eliminate duplicate records and fetch only unique ones.

Complete Python Course with Advance topics:-Click Here
SQL Tutorial :-Click Here

Using DISTINCT to Remove Duplicates

The DISTINCT keyword helps retrieve unique values from a specific column or a combination of columns. Below is the syntax:

SELECT DISTINCT column1, column2, ....columnN  
FROM table_name  
WHERE [conditions];  

Example

Let’s consider a EMPLOYEE table with duplicate salary records.

EMP_ID	NAME	SALARY	CITY
101	RAHUL VERMA	50000	MUMBAI
102	NEHA SINGH	48000	DELHI
103	ARJUN SHARMA	50000	BANGALORE
104	SAKSHI JAIN	52000	KOLKATA
105	ROHAN MEHTA	48000	PUNE
106	KRITI AGGARWAL	51000	CHENNAI

Checking for Duplicate Salary Records

Before applying DISTINCT, let’s retrieve all salary records to check for duplicates:

SELECT SALARY FROM EMPLOYEE  
ORDER BY SALARY;  

Output:

SALARY
48000
48000
50000
50000
51000
52000

Using DISTINCT to Remove Duplicates

Now, we apply the DISTINCT keyword to fetch unique salary records:

SELECT DISTINCT SALARY FROM EMPLOYEE  
ORDER BY SALARY;  

Output:

SALARY
48000
50000
51000
52000

Duplicate salary values have been removed, as can be seen above.

Download New Real Time Projects :-Click here
Complete Advance AI topics:- CLICK HERE

Conclusion

In order to preserve data integrity, SQL must handle duplicate records. The DISTINCT keyword is a simple yet powerful solution to fetch unique records from a table, ensuring accurate and meaningful data retrieval.

For more SQL tutorials and updates, stay tuned to UpdateGadh!

---

sql delete duplicate rows keep one
delete duplicate rows in sql w3schools
to remove duplicate rows in sql select statement
sql delete duplicate rows with same id
sql delete duplicate rows but keep one without primary key
sql delete duplicate rows based on one column
delete duplicate rows in oracle
delete duplicate records in sql server using row_number
sql delete duplicate rows but keep one
cte sql
sql delete duplicate rows oracle