1,2,3,4,5,6,7,8,9
2,3,4,5,6,7,8,9,1
3,4,5,6,7,8,9,1,2
4,5,6,7,8,9,1,2,3
5,6,7,8,9,1,2,3,4
6,7,8,9,1,2,3,4,5
7,8,9,1,2,3,4,5,6
8,9,1,2,3,4,5,6,7
9,1,2,3,4,5,6,7,8

B1ts, would you be kind to give some simple example where rows and columns are valid but little squares not?
Edit: It can be find in previous comments.

If you look at description, it shows a 9x9 sudoku example. It contains 9 rows, which must have unique numbers, 9 columns, and also 9 3x3 'little squares', which should also have only unique numbers. Obviously, with larger sizes, those little squares will also have bigger dimensions (you have to calculate how big). For example, the first square in description is:

[7,8,4,
 5,3,9,
 6,1,2]

Does that make it any clearer?