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Oct 13, 2020 · What Is a Self Join in SQL? The self join, as its name implies, joins a table to itself. To use a self join, the table must contain a column (call it X) that acts as the primary key and a different column (call it Y) that stores values that can be matched up with the values in Column X.
SQL Self Join Example. The following SQL statement matches customers that are from the same city: Example Get your own SQL Server. SELECT A.CustomerName AS CustomerName1, B.CustomerName AS CustomerName2, A.City. FROM Customers A, Customers B. WHERE A.CustomerID <> B.CustomerID. AND A.City = B.City. ORDER BY A.City; Try it Yourself »
Jun 27, 2024 · SQL Self Join. Last Updated : 27 Jun, 2024. Joins in SQL, a self join is a regular join that is used to join a table with itself. It basically allows us to combine the rows from the same table based on some specific conditions.
This tutorial explains SQL self-join technique and shows you how to apply the self-join to join a table to itself using the INNER JOIN or LEFT JOIN clause.
SQL Server self join examples. Let’s take some examples to understand how the self join works. 1) Using self join to query hierarchical data. Consider the following staffs table from the sample database: The staffs table stores the staff information such as id, first name, last name, and email.
Sep 21, 2017 · What is a SQL self join and how does it work? When should you use a self join in SQL? In this article, you’ll find answers to these questions!
A SQL SELF JOIN is a type of join operation where a table is joined with itself. It allows you to combine data from a single table by creating a virtual copy of the table and establishing relationships between the original and virtual tables.
