Join is SQL is a clause that is used to combined two or more table rows based on the related column between them ( generally use primary key ) There are four types Left Join --- fetch all of the rows from the left table and only matching rows from right Right Join -- fetch all of the rows from the right table and only match rows from left Inner join -- fetch only matched rows between them Outer Join -- fetch all the unmatched rows between the tables Left Outer join -- fetch all the unmatched rows from the left table Right Outer Join -- fetch all the unmatched rows from the right table