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SQL INNER JOIN

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INNER JOIN

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

Let's look at a selection of the Products table:

ProductID ProductName CategoryID Price
1 Chais 1 18
2 Chang 1 19
3 Aniseed Syrup 2 10

And a selection of the Categories table:

CategoryID CategoryName Description
1 Beverages Soft drinks, coffees, teas, beers, and ales
2 Condiments Sweet and savory sauces, relishes, spreads, and seasonings
3 Confections Desserts, candies, and sweet breads

We will join the Products table with the Categories table, by using the CategoryID field from both tables:

Example

Join Products and Categories with the INNER JOIN keyword:

SELECT ProductID, ProductName, CategoryName
FROM Products
INNER JOIN Categories ON Products.CategoryID = Categories.CategoryID;
Try it Yourself »

SQL INNER JOIN

Note: The INNER JOIN keyword returns only rows with a match in both tables. Which means that if you have a product with no CategoryID, or with a CategoryID that is not present in the Categories table, that record would not be returned in the result.

Syntax

SELECT column_name(s)
FROM table1
INNER JOIN table2
ON table1.column_name = table2.column_name;

Naming the Columns

It is a good practice to include the table name when specifying columns in the SQL statement.

Example

Specify the table names:

SELECT Products.ProductID, Products.ProductName, Categories.CategoryName
FROM Products
INNER JOIN Categories ON Products.CategoryID = Categories.CategoryID;
Try it Yourself »

The example above works without specifying table names, because none of the specified column names are present in both tables. If you try to include CategoryID in the SELECT statement, you will get an error if you do not specify the table name (because CategoryID is present in both tables).

JOIN or INNER JOIN

JOIN and INNER JOIN will return the same result.

INNER is the default join type for JOIN, so when you write JOIN the parser actually writes INNER JOIN.

Example

JOIN is the same as INNER JOIN:

SELECT Products.ProductID, Products.ProductName, Categories.CategoryName
FROM Products
JOIN Categories ON Products.CategoryID = Categories.CategoryID;
Try it Yourself »

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);
Try it Yourself »

Test Yourself With Exercises

Exercise:

Choose the correct JOIN clause to select all records from the two tables where there is a match in both tables.

SELECT *
FROM Orders

ON Orders.CustomerID=
Customers.CustomerID;

Start the Exercise


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