Inner Join is the first and most common type of join. The INNER JOIN keyword selects records that have matching values in both or among tables.
Syntax
SELECT column_list FROM table1 INNER JOIN table2 ON (conditions);
Let’s examine the statement above in detail:
The following SQL statement selects all orders with customer and shipper information:
SELECT column_list FROM table1 INNER JOIN table2 ON (conditions_1) INNER JOIN table3 ON (conditions_2) INNER JOIN table4 ON (conditions_3)