SQL Join

SQL Join is a powerful feature that allows data from two or more tables to be combined into a single result set. This can be useful for querying related data from multiple tables in a database.

Types of Joins

There are several types of joins in SQL, including:

Inner Join

The inner join returns only the rows that have matching values in both tables. The syntax for an inner join is:

SELECT columns
FROM table1
INNER JOIN table2
ON condition;

Left Join

The left join returns all rows from the left table and the matching rows from the right table. If there is no match in the right table, NULL values are returned. The syntax for a left join is:

SELECT columns
FROM table1
LEFT JOIN table2
ON condition;

Right Join

The right join returns all rows from the right table and the matching rows from the left table. If there is no match in the left table, NULL values are returned. The syntax for a right join is:

SELECT columns
FROM table1
RIGHT JOIN table2
ON condition;

Full Outer Join

The full outer join returns all rows from both tables, with NULL values for the columns that do not have a match in the other table. The syntax for a full outer join is:

SELECT columns
FROM table1
FULL OUTER JOIN table2
ON condition;

Joining Multiple Tables

You can also join multiple tables together by using multiple join statements. For example, if you have three tables named table1, table2, and table3, you could join them together like this:

SELECT columns
FROM table1
INNER JOIN table2
ON condition
INNER JOIN table3
ON condition;

Conclusion

SQL join is a powerful feature that allows you to combine data from multiple tables in a database. There are several types of joins, including inner, left, right, and full outer join. You can also join multiple tables together by using multiple join statements.