SQL JOIN for Beginners Part 2: Types of Joins

JOIN in SQL is used to combine rows from two or more tables based on a related column.
The main types of JOIN are as follows:

Using Venn Diagrams can make understanding much easier.

You can explore examples with diagrams and SQL statements on SQL Joins Visualizer.

1. INNER JOIN

• Retrieves only the data where keys match in both tables A and B.

• Excludes rows that exist only in A or only in B.

2. LEFT JOIN(LEFT OUTER JOIN)

• Retrieves all data from the left table (A).

• If the key from A exists in B, the corresponding data from B is included.

• Includes rows that exist only in A.

3. RIGHT JOIN(RIGHT OUTER JOIN)

• Retrieves all data from the right table (B).

• If the key from B exists in A, the corresponding data from A is included.

• Includes rows that exist only in B.

4. FULL OUTER JOIN

• Retrieves all data from both tables.

• Includes both matching rows and non-matching rows from A and B.

Next, we will learn more about JOIN statements in detail through practical examples :)