INNER JOIN, FULL OUTER JOIN

INNER JOIN 
SYNTAX
SELECT comma_separeted_column_names
FROM table1
INNER JOIN table2 
ON table1.column_name = table2.column_name;

EXAMPLE

SELECT user.username, orders.order_id

FROM users
INNER JOIN orders 

ON users.id = orders.order_id
ORDER BY users.username;

Note: Here this query will retrieve only those records which have matching both the tables.


FULL OUTER JOIN 
SYNTAX
SELECT comma_separeted_column_names
FROM table1
OUTER JOIN table2 
ON table1.column_name = table2.column_name;

EXAMPLE

SELECT user.username, orders.order_id

FROM users
FULL OUTER JOIN orders 

ON users.id = orders.order_id
ORDER BY users.username;

Note: Here this query will retrieve all the records from both the table if there is at least one matching record among both tables.