MariaDB JOINS 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
INNER JOIN The INNER Join is the most common one. It returns all the rows from multiple tables where the join condition is met.
Syntax:
SELECT expr_1, expr_2, ... expr_n FROM table_1 INNER JOIN table_2 ON join_predicate;
Example: Players Table:
ID NAME SPORTS 1 Sachin Cricket 2 Dhoni Cricket 3 Sunil Football 4 Srikanth Badminton 5 Mary Boxing
Trainers Table:
TRAINER_ID TRAINER_NAME TRAINER_SPORTS 101 Bond Football 102 Smith Badminton 103 Brand Boxing
Query:
SELECT players.id, players.name, trainers.trainer_id FROM players INNER JOIN trainers ON players.sports = trainers.trainer_sports; |
Output:
ID NAME TRAINER_ID 3 Sunil 101 4 Srikanth 102 5 Mary 103
Explanation: 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.
