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