Difference Between Inner and Outer Join in SQL

In Relational database tables are associated with each other and we used foreign key to maintain relationships between tables. We used join clause to retrieve data from associated tables. The join condition indicates how column in each table are matched against each other. 

There are two types of joins clause in SQL 

  • Inner join 
  • Outer join

Outer join is again divided into parts −

  • LEFT OUTER JOIN - It will return all data of the left table and matched  records in both table 
  • RIGHT OUTER JOIN - it will return all the data of the right table and matched records in both table
Sr. No.
 Key
 Inner join
 Outer join

1

Basic 

It can be used to retrieve only matched records between both tables 

It is used to retrieve all matching records as well non matching records of the tables  

2

        Return 

It doesn't return anything when match is not found.

It return null in the column values 

3

Performance 

It is faster than outer join.

It is slower than inner join because of the larger result set

Example of OUTER JOIN

SELECT columnnameList
FROM tableA
FULL OUTER JOIN tableB
ON tableA.column_name = tableB.column_name
WHERE condition;

Example of INNER JOIN

SELECT columnlist
FROM TableA
INNER JOIN
TableB ON join condition
Updated on: 2020-01-21T09:41:05+05:30

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