To retrieve data from multiple tables, the MariaDB Join Query is used.
Types of Joins:
There are mainly three types of Joins that the MariaDB database supports. These are:
- Inner or Simple Join
- Left Outer Join or Left Join
- Right Outer Join or Right Join
The INNER Join is the most common one. It returns all the rows from multiple tables where the join condition is met.
SELECT expr_1, expr_2, ... expr_n FROM table_1 INNER JOIN table_2 ON join_predicate;
ID NAME SPORTS 1 Sachin Cricket 2 Dhoni Cricket 3 Sunil Football 4 Srikanth Badminton 5 Mary Boxing
TRAINER_ID TRAINER_NAME TRAINER_SPORTS 101 Bond Football 102 Smith Badminton 103 Brand Boxing
SELECT players.id, players.name, trainers.trainer_id FROM players INNER JOIN trainers ON players.sports = trainers.trainer_sports;
ID NAME TRAINER_ID 3 Sunil 101 4 Srikanth 102 5 Mary 103
The PLAYERS and the TRAINERS are the already existing tables. The selected fields of the rows satisfying the conditions will be added to the result set, on joining.