Introduction:
A join query is used to combine rows from two or more tables based on a related column between them. The join condition specifies the relationship between the tables and determines which rows will be included in the result set. However, in some cases, there may be no join condition specified, resulting in a specific type of join known as a Cartesian join.

Cartesian Join:
A Cartesian join, also known as a cross join or a cross product, is a join operation that returns the Cartesian product of the two tables involved. It means that every row from the first table is combined with every row from the second table, resulting in a potentially large result set. The Cartesian join does not require any join condition to be specified.

Example:
Consider two tables, Table A and Table B, with the following data:

Table A:
| ID | Name |
|----|--------|
| 1 | Alice |
| 2 | Bob |

Table B:
| ID | City |
|----|---------|
| 1 | London |
| 2 | Paris |

If we perform a Cartesian join between these two tables without specifying a join condition, the result would be:

| ID | Name | ID | City |
|----|--------|----|---------|
| 1 | Alice | 1 | London |
| 1 | Alice | 2 | Paris |
| 2 | Bob | 1 | London |
| 2 | Bob | 2 | Paris |

As we can see, every row from Table A is combined with every row from Table B, resulting in a total of four rows in the output.

Equijoins:
On the other hand, equijoins are a type of join where a join condition is specified using the equality operator (=) to match rows based on the values of the specified columns. Equijoins are the most common type of join and require a join condition to be specified.

No Join Condition:
The question asks which product is returned in a join query that has no join condition. Since equijoins always require a join condition, the correct answer is option B - Cartesian join. In a Cartesian join, every possible combination of rows from the two tables is returned, resulting in a large result set.

Conclusion:
In conclusion, a join query with no join condition results in a Cartesian join. This type of join returns the Cartesian product of the two tables involved, where every row from the first table is combined with every row from the second table. Equijoins, on the other hand, require a join condition to be specified using the equality operator (=) to match rows based on the values of the specified columns.