A join is a query that combines rows from two or more tables. In a join query, more than one tables are listed in FROM clause. The function of combining data from multiple tables is
called joining. SQL can obtain data from several related tables by performing either a physical or virtual join on the tables.
Joins are used when we have to select data from two or more tables. Joins are used to extract data from two (or more) tables, when we need a relationship between certain columns
in these tables.
The SQL Join condition is always used in the WHERE clause of SELECT, UPDATE and DELETE statements.
There are different kind of SQL joins are as follows:
1. Cartesian Product (Cross Product)
2. Equi Join
3. Self Join
4. Non-Equi Join
5. Natural Join