A database operation that allows you to retrieve and modify data from more than one table at a time using a single Structured Query Language (SQL) SELECT statement.
You can use the Microsoft Query tool for Microsoft SQL Server to graphically create joins for transact-SQL queries that join two or more tables or join a table to itself.
Joins are a necessity because a single table might not provide all the information you want to retrieve about a specific database entity.
By connecting tables using joins, you can retrieve information that resides in more than one table in a single operation.
You can create three kinds of joins:
There are two kinds of syntax for creating joins, ANSI join syntax and SQL Server join syntax. You can use only one of these types of syntax in a given SELECT statement.