INNER JOIN vs LEFT JOIN in SQL

SQL JOINs allow you to retrieve related data from multiple tables. Here’s a clear comparison between INNER JOIN and LEFT JOIN with examples.

🔹 INNER JOIN

• Returns only the rows where there is a match in both tables.
• If no match exists, that row is excluded from the result.
• Example:

SELECT e.name, d.department_name
FROM employees e
INNER JOIN departments d
   ON e.dept_id = d.id;

👉 Shows employees only if they belong to a department.

🔹 LEFT JOIN

• Returns all rows from the left table and the matching rows from the right table.
• If no match is found, columns from the right table become NULL.
• Example:

SELECT e.name, d.department_name
FROM employees e
LEFT JOIN departments d
   ON e.dept_id = d.id;

👉 Shows all employees, even those without a department.