What are some examples of SQL joins?

What are some examples of SQL joins?

SQL joins are used to combine rows from two or more tables based on a related column. Here are some examples:

1. INNER JOIN: Returns records that have matching values in both tables.
2. LEFT JOIN: Returns all records from the left table and matched records from the right table.
3. RIGHT JOIN: Returns all records from the right table and matched records from the left table.
4. FULL OUTER JOIN: Returns all records when there is a match in either left or right table records.

Can you give me a specific example of an INNER JOIN?

Sure! Suppose we have two tables: Employees and Departments. An INNER JOIN can be used to find employees along with their department names:

SELECT Employees.Name, Departments.DepartmentName
FROM Employees
INNER JOIN Departments ON Employees.DepartmentID = Departments.ID;

What about a LEFT JOIN example?

Absolutely! Using the same tables, a LEFT JOIN would look like this:

SELECT Employees.Name, Departments.DepartmentName
FROM Employees
LEFT JOIN Departments ON Employees.DepartmentID = Departments.ID;

This will return all employees, including those who may not belong to any department.

How do I perform a FULL OUTER JOIN?

A FULL OUTER JOIN retrieves all records from both tables, with matching records where available. Here's an example:

SELECT Employees.Name, Departments.DepartmentName
FROM Employees
FULL OUTER JOIN Departments ON Employees.DepartmentID = Departments.ID;

This will show all employees and all departments, even if there are no matches.