A cross product join returns a result set that produces all possible combinations of rows from the two tables. The number of rows in the result set is the product of the number of rows in the first table and the number of rows in the second table.
The FinancialData and FinancialCodes in the sample database contain financial data for a fictitious company. Both tables have a code column that you can use to join the two tables.
The following SELECT statement lists all the data in the FinancialCodes and FinancialData tables:
SELECT * FROM FinancialCodes, FinancialData
The result set matches every row in the FinancialCodes table with every row in the FinancialData table. This join is called a full cross product, also known as a Cartesian product. Each row consists of all columns from the FinancialCodes table followed by all columns from the FinancialData table.
The cross product join is a simple starting point for understanding joins, but it is not very useful in itself. More selective joins apply restrictions to the cross product table.