This tutorial gives an overview of different types of table joins that can be used to query data in different tables in a database and demonstrates the same
Relational data is distributed across different tables. Queries typically reference information located in atleast two to three related tables. Manual sorting of such data are prone to errors. Hence, queries that provide results by collecting information from all related tables is quite essential.
In order retrieve data from multiple tables, different types of table joins are used in SELECT statements
One of the more powerful features of the SELECT statement (and the element that makes data normalization possible) is the ability to retrieve data from two or more tables by performing what is known as a join operation. This operation enables selective retrieval of information from all related tables efficiently.
There are different types of joins depending on the kind of information required to be retrieved :