The SQL Joins is used to
combine records from two or more tables in a database. A JOIN is a means for joining
fields from two tables by using values common to each. It is visible that the
join is performed in the WHERE clause. Several operators can be used to join
tables, such as =, <, >, <>, <=, >=, !=, BETWEEN, LIKE, and
NOT; they can all be used to join tables. However, the most common operator is
the equal symbol.
SQL Join Types:
There
are different types of joins available in SQL:
·
INNER JOIN: returns rows when there is a match in
both tables.
·
LEFT JOIN: returns all rows from the left table,
even if there are no matches in the right table.
·
RIGHT JOIN: returns all rows from the right table,
even if there are no matches in the left table.
·
FULL JOIN: returns rows when there is a match in
one of the tables.
· SELF JOIN: is used to join a table to itself as
if the table were two tables, temporarily renaming at least one table in the
SQL statement.
·
CARTESIAN JOIN: returns the Cartesian product of the
sets of records from the two or more joined tables.
