MySQL Natural Join

The NATURAL JOIN in MySQL is a type of join operation that combines rows from two or more tables based on columns with the same names. It automatically matches columns with the same names in both tables, and it is typically used when the tables have related data and share common column names.

The basic syntax of a NATURAL JOIN is as follows:

SELECT columns
FROM table1
NATURAL JOIN table2;

In this syntax:

• SELECT columns: Specifies the columns you want to retrieve from the joined tables.
• FROM table1: Indicates the first table you want to include in the join.
• NATURAL JOIN table2: Specifies the second table you want to join with the first table using columns with the same names.

Here’s an example of using a NATURAL JOIN. Suppose you have two tables, employees and departments, and both tables have a column named department_id. You want to retrieve the names of employees and their corresponding department names:

SELECT employee_name, department_name
FROM employees
NATURAL JOIN departments;

In this example, the NATURAL JOIN automatically matches rows based on the department_id column, which is shared between the two tables. This produces a result set that includes the names of employees and their corresponding department names.

It’s important to note the following:

• A NATURAL JOIN only works with columns that have the same name in both tables. If a column exists in one table but not in the other, it will not be included in the join condition.
• While NATURAL JOINs can be convenient when columns have identical names, they lack the explicitness and transparency of specifying the join condition explicitly using the ON clause. Therefore, many developers prefer using the ON clause for clarity and to avoid unexpected results when column names change.
• The use of NATURAL JOINs can be risky in larger databases where column name changes or the addition of new columns can lead to unexpected results. For these reasons, many developers opt for explicitly defined INNER JOIN operations using the ON clause.