Generating All Possible Combinations: A Cross Join Challenge

Often in data analysis and application development, you need to generate every possible pairing of items from two distinct sets. This is particularly useful for tasks like creating default configurations, generating test data, or exploring all potential combinations in a combinatorial problem. This challenge will test your ability to use SQL's CROSS JOIN to achieve this comprehensive pairing.

Problem Description

Your task is to write a SQL query that generates a Cartesian product (all possible combinations) between two tables: Colors and Sizes. The Colors table contains a list of available colors, and the Sizes table contains a list of available sizes. Your query should output a result set where each row represents a unique combination of one color and one size.

Key Requirements:

• You must use a CROSS JOIN to combine the Colors and Sizes tables.
• The output should include a column for the color name and a column for the size name.
• Every color should be paired with every size.

Expected Behavior:

The output should be a list of all possible (color, size) pairs. If there are N colors and M sizes, the output should contain N * M rows.

Edge Cases to Consider:

• What happens if one of the tables is empty? (Your query should ideally handle this gracefully, producing an empty result set).

Examples

Example 1:

Input Tables:

Colors:
| color_id | color_name |
|----------|------------|
| 1        | Red        |
| 2        | Blue       |

Sizes:
| size_id | size_name |
|---------|-----------|
| 101     | S         |
| 102     | M         |
| 103     | L         |

Output:

| color_name | size_name |
|------------|-----------|
| Red        | S         |
| Red        | M         |
| Red        | L         |
| Blue       | S         |
| Blue       | M         |
| Blue       | L         |

Explanation:
Each color ('Red', 'Blue') is paired with each size ('S', 'M', 'L'), resulting in 2 * 3 = 6 combinations.

Example 2:

Input Tables:

Colors:
| color_id | color_name |
|----------|------------|
| 1        | Green      |

Sizes:
| size_id | size_name |
|---------|-----------|
| 201     | XL        |
| 202     | XXL       |

Output:

| color_name | size_name |
|------------|-----------|
| Green      | XL        |
| Green      | XXL       |

Explanation:
The single color 'Green' is paired with each of the two sizes ('XL', 'XXL'), resulting in 1 * 2 = 2 combinations.

Example 3: Empty Table Scenario

Input Tables:

Colors:
| color_id | color_name |
|----------|------------|
| 1        | Yellow     |
| 2        | Purple     |

Sizes:
(This table is empty)

Output:

(An empty result set)

Explanation:
When one of the tables involved in a CROSS JOIN is empty, the resulting Cartesian product is also empty.

Constraints

• The Colors table will have at least one column named color_name.
• The Sizes table will have at least one column named size_name.
• The number of rows in Colors will not exceed 1000.
• The number of rows in Sizes will not exceed 1000.
• The generated query should be efficient for the given constraints.

Notes

• A CROSS JOIN does not require an ON clause because it produces all possible combinations without any specific matching condition.
• Consider how the output column names should be presented.
• Think about how the CROSS JOIN operation logically builds the final result set.