Plug: Check out the Tableau Visualization I made using this data.

It's nothing groundbreaking, but it was satisfying and bit challenging to make.
Oh, and it sometimes tends to break for seasons with number of clubs < 20.
Shhhh.

Tip: Although you can use Python to scrape this data (as I did in first few attempts), a better and more feasible method in my opinion would be to use IMPORTHTML tool in G-Sheets.

The dataset contains league table and match results of all seasons in the Spanish Football League, or LaLiga as it's known.

All seasons are included, starting from the inaugural 1929-30 to the recently wrapped 2019-20.
Exceptions: 1936-37, 1937-38, 1938-39 due to the Spanish Civil War.

Data was scraped from Wikipedia, and is as error-proof as humanly possible.