How to Find Duplicate Rows in SQL

Duplicate rows in a database can be a real headache. They can cause errors in your data, lead to incorrect results, and generally make a mess of things. Fortunately, SQL has a handy way of finding and removing duplicate rows.

The Solution

The solution is to use the SELECT DISTINCT clause. This clause takes a list of columns as its argument, and returns only the unique combinations of values in those columns. For example, if you wanted to find all the duplicate rows in a table called users, you would use the following query:

SELECT DISTINCT * FROM users;

Examples

Let's look at a few examples of how this clause can be used. Suppose you have a table called users with the following data:

If you wanted to find the duplicate rows in this table, you would use the following query:

SELECT DISTINCT * FROM users;

This query would return the following result:

As you can see, the duplicate row (John, 25) has been removed.

Additional Info

The SELECT DISTINCT clause is supported by most major databases, including MySQL, PostgreSQL, and SQL Server. However, the syntax may vary slightly depending on the database you are using. For more information, check out the documentation for your particular database. 🤓