INNER JOIN

Inner joins compare the rows from two tables based on conditions specified in the query. Typically, this type of join would be used to intersect rows that have the same value in a specific column or set of columns. The only rows that would be returned are the ones that have matching rows in both tables, as represented in black in the following diagram:

For example, the AdventureWorks sample database has a Product table that contains the ProductID and Name columns and a ProductInventory table that contains the ProductID and Quantity columns. To write a query that returns the product name and the quantity together, an inner join can be used to combine rows from the Product table with rows from the ProductInventory table based on matching values in the ProductID column. In this case, only products that have rows in both tables will be returned. The query would look like the following:

SELECT Name AS ProductName, Quantity
FROM Production.Product
INNER JOIN Production.ProductInventory ON Product.ProductID = ProductInventory.ProductID;