Implementation of join operation
The join operation is used to combine rows from two or more tables based on a related column between them. There are several types of join operations, including:
1. Inner Join: Returns only the rows that have matching values in both tables. The syntax for inner join is as follows:
SELECT *
FROM table1
INNER JOIN table2
ON table1.column = table2.column;
2. Left Join: Returns all the rows from the left table and the matched rows from the right table. If there is no match, NULL values are returned. The syntax for left join is as follows:
SELECT *
FROM table1
LEFT JOIN table2
ON table1.column = table2.column;
3. Right Join: Returns all the rows from the right table and the matched rows from the left table. If there is no match, NULL values are returned. The syntax for right join is as follows:
SELECT *
FROM table1
RIGHT JOIN table2
ON table1.column = table2.column;
4. Full Outer Join: Returns all the rows from both tables and NULL values for non-matching rows. The syntax for full outer join varies across different database systems.
These join operations can be implemented in most relational databases using SQL. The specific syntax may vary slightly depending on the database system being used.