Question

What is the result of a query that selects from two tables but includes no join condition?

A.A selection of matched rows from both tables
B.A selection of rows from the first table only
C.A Cartesian product
D.A syntax error

Answer 1

The result of a query that selects from two tables but includes no join condition is a Cartesian product. This means all possible combinations of rows from both tables are included in the result set.

Step-by-step explanation:

When a query selects from two tables but includes no join condition, the result is what's known as a Cartesian product. This occurs because every row from the first table is paired with every row from the second table, producing a result set that has the number of rows equal to the product of the number of rows in both tables. For example, if one table has 5 rows and the other has 3, the Cartesian product will have 15 rows.

Let's consider two tables, Table1 with columns A and B, and Table2 with columns C and D. If a query is run without a join condition as follows:

SELECT * FROM Table1, Table2;

The result will be a Cartesian product that contains all possible combinations of the rows from Table1 and Table2.