What are Joins? Discuss all types of Joins with the help of suitable examples.

Joins in SQL are used to combine rows from two or more tables, based on a related column between them. There are four types of Joins in SQL: INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN.

1. INNER JOIN: The INNER JOIN keyword selects records that have matching values in both tables.

Example:

SELECT Orders.OrderID, Customers.CustomerName
FROM Orders
INNER JOIN Customers
ON Orders.CustomerID = Customers.CustomerID;

This SQL statement would return the order number and the customer name for all orders where there is a matching customer ID in both the "Orders" and "Customers" tables.

2. LEFT JOIN (or LEFT OUTER JOIN): The LEFT JOIN keyword returns all records from the left table (table1), and the matched records from the right table (table2). The result is NULL from the right side, if there is no match.

Example:

SELECT Customers.CustomerName, Orders.OrderID
FROM Customers
LEFT JOIN Orders
ON Customers.CustomerID = Orders.CustomerID;

This SQL statement would return all customer names and any matching order IDs. If there is no match, the result is NULL on the right side.

3. RIGHT JOIN (or RIGHT OUTER JOIN): The RIGHT JOIN keyword returns all records from the right table (table2), and the matched records from the left table (table1). The result is NULL from the left side, when there is no match.

Example:

SELECT Orders.OrderID, Customers.CustomerName
FROM Orders
RIGHT JOIN Customers
ON Orders.CustomerID = Customers.CustomerID;

This SQL statement would return all order IDs and any matching customer names. If there is no match, the result is NULL on the left side.

4. FULL JOIN (or FULL OUTER JOIN): The FULL JOIN keyword returns all records when there is a match in

Joins in SQL are used to combine rows from two or more tables, based on a related column between them. There are four basic types of SQL joins: INNER, LEFT, RIGHT, and FULL.

1. INNER JOIN: The INNER JOIN keyword selects records that have matching values in both tables.

Example:

SELECT Orders.OrderID, Customers.CustomerName
FROM Orders
INNER JOIN Customers
ON Orders.CustomerID = Customers.CustomerID;

This SQL statement would return the order number and the customer name for all orders where there is a matching customer ID in both the "Orders" and "Customers" tables.

2. LEFT JOIN (or LEFT OUTER JOIN): The LEFT JOIN keyword returns all records from the left table (table1), and the matched records from the right table (table2). The result is NULL from the right side, if there is no match.

Example:

SELECT Customers.CustomerName, Orders.OrderID
FROM Customers
LEFT JOIN Orders
ON Customers.CustomerID = Orders.CustomerID;

This SQL statement would return all customer names and any matching order numbers. If there is no match, the result is NULL on the right side.

3. RIGHT JOIN (or RIGHT OUTER JOIN): The RIGHT JOIN keyword returns all records from the right table (table2), and the matched records from the left table (table1). The result is NULL from the left side, when there is no match.

Example:

SELECT Orders.OrderID, Customers.CustomerName
FROM Orders
RIGHT JOIN Customers
ON Orders.CustomerID = Customers.CustomerID;

This SQL statement would return all order numbers and any matching customer names. If there is no match, the result is NULL on the left side.

4. FULL JOIN (or FULL OUTER JOIN): The FULL JOIN keyword returns all records when there is a match in either left (table1) or right (table2) table records.

Example:

SELECT Customers.CustomerName, Orders.OrderID
FROM Customers
FULL JOIN Orders
ON Customers.CustomerID = Orders.CustomerID;

This SQL statement would return all customer names and order numbers, and it would return NULL in either column when there is no match.