Difference between Natural join and Cross join in SQL

A JOIN clause is used to combine rows from two or more tables, based on a related data column in between them. Natural Join and Cross Join both serve different purposes in database management. While the former matches column with same name, the latter outputs all possible row combinations between two tables.

Natural Join

Natural Join joins two tables based on same attribute name and data types. The resulting table will contain all the attributes of both the tables but only one copy of each common column. It is denoted by a symbol (⨝). It is the combination of projection and filtered cartesian product.

Natural Join is beneficial when you need to:

• Simplify Queries: It eliminates the condition to match the records.
• Reduce Errors: It automatically matches columns with the same name, reducing error.
• Improve Readability: It simplifies SQL code, making it more readable and understandable.

Example

Consider the two tables given below:

Table A (Employees)

Table B(Departments)

Consider the given query

SELECT *
FROM Employees E NATURAL JOIN Departments D;

Output :

Result of the Natural Join on both table

Cross Join

Cross Join will produce cross or Cartesian product of two tables if there is no condition specifies. The resulting table will contain all the attributes of both the tables including duplicate or common columns also.

Example

Consider the two tables and the query is given below:

Student Table:

Marks Table:

SELECT *
FROM Student S CROSS JOIN Marks M;

Output:

Difference between Natural Join and Cross Join in SQL