SQL INNER JOIN Keyword

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SQL inner join is used to retrieve only the matching rows from two or more tables based on a common column between them. It returns only the rows where the specified column has matching values in both tables being joined. The syntax for an inner join is as follows:

SELECT column1, column2, ...

FROM table1

JOIN table2

ON table1.common_column = table2.common_column;

IN THIS SYNTAX:

·       SELECT specifies the columns you want to get from the resulting join.

·       FROM specifies the first table you want to join.

·       JOIN is used to specify the type of join, this case is an inner join.

·       table2 is the second table you want to join.

·       ON is used to specify the condition for joining the tables, which is the common column between them (common_column in this example). This condition determines which rows from both tables will be included in the result set.

For example, let's say you have two tables, orders and customers, and you want to retrieve information about orders along with the corresponding customer information for orders that have a matching customer in the customers table. You can use an inner join as follows:

SELECT orders.order_id,

orders.order_date,

customers.customer_name

FROM orders

JOIN customers

ON orders.customer_id = customers.customer_id;

This query will retrieve the order_id and order_date from the orders table, and the customer_name from the customers table for orders that have a matching customer_id in both tables. Only the rows where there is a match in both tables will be included in the result set.

JOIN Three Tables 

The following SQL statement selects all orders with customer and shipper information: 

Example 

SELECT Orders.OrderID, Customers.CustomerName, Shippers.ShipperName

FROM ((Orders

INNER JOIN Customers ON Orders.CustomerID = Customers.CustomerID)

INNER JOIN Shippers ON Orders.ShipperID = Shippers.ShipperID);

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