✖️ CROSS JOIN – Combining Every Row from Both Tables<

(because sometimes you want every possible combination of rows)

🔧 Quick Syntax

SELECT columns
FROM table1
CROSS JOIN table2;

This tells SQL:
“Give me every possible combination of rows from both tables.”

👀 Imagine You Have Two Tables:

🧑 colors table:

color_id	color_name
1	Red
2	Blue

🛠️ shapes table:

shape_id	shape_name
1	Circle
2	Square

In this case, we have:
– 2 colors: Red, Blue
– 2 shapes: Circle, Square

🔄 What Does a CROSS JOIN Do?

A CROSS JOIN creates every possible combination of rows between the two tables.
It takes every row from the colors table and combines it with every row from the shapes table.

🔧 CROSS JOIN Example

Let’s say we want to create a list of all possible combinations of colors and shapes.

SELECT colors.color_name, shapes.shape_name
FROM colors
CROSS JOIN shapes;

What will happen is:
– The first color (Red) will be combined with both shapes: Circle and Square
– Then, the second color (Blue) will be combined with both shapes: Circle and Square.

✅ Result:

color_name	shape_name
Red	Circle
Red	Square
Blue	Circle
Blue	Square

🔁 Why Use CROSS JOIN?

• When you need to generate combinations of data — like product bundles or testing combinations of options.
• Be cautious: If you have large tables, a CROSS JOIN can quickly multiply the number of rows. For example, 100 rows in one table and 50 rows in another will give you 5,000 rows in your result set.

🧃 Recap

• CROSS JOIN gives you every possible combination of rows from both tables.
• It’s perfect for generating combinations, like creating product bundles or testing different combinations of options.
• Be careful with large tables, as it can generate huge result sets.