Why should you care?

Useful for generating combinations (sizes × colors) or a small numbers table — dangerous on large tables.

See it live — copy this example

Run in SQL Server Management Studio (SSMS) or Azure Data Studio.

USE DataVerse;
IF OBJECT_ID(N'dbo.Sizes', N'U') IS NOT NULL DROP TABLE dbo.Sizes;
IF OBJECT_ID(N'dbo.Colors', N'U') IS NOT NULL DROP TABLE dbo.Colors;
CREATE TABLE dbo.Sizes (SizeCode CHAR(1) PRIMARY KEY);
CREATE TABLE dbo.Colors (ColorName NVARCHAR(20) PRIMARY KEY);
INSERT INTO dbo.Sizes VALUES ('S'), ('M'), ('L');
INSERT INTO dbo.Colors VALUES (N'Red'), (N'Blue');
SELECT s.SizeCode, c.ColorName
FROM dbo.Sizes AS s
CROSS JOIN dbo.Colors AS c
ORDER BY s.SizeCode, c.ColorName;

What happened?

• 3 sizes × 2 colors = 6 rows.
• Each pair is a potential SKU variant.
• Never CROSS JOIN million-row tables by accident.

Practice next

1. Run the example and count 6 rows.
2. Add a third color and rerun (9 rows).
3. Intentionally CROSS JOIN Orders to Products without need — then cancel if huge.
4. CROSS JOIN a tally of 1..5 for demo date offsets.
5. Insert results into ProductVariants.

Remember

CROSS JOIN multiplies row counts. Good for small dimension combos. Guard against accidental use on large sets.

Apparel size × color matrix

Merchandising builds DataVerse variants from Sizes × Colors.

Outcome: All valid SKUs generated in one set-based insert.