When I log into my bank's website, I have access to my data on their databases. Logging in gives me access. No search engine can see that data. I'm trying to understand the difference between my bank's databases and SOL's.
It's not about databases, it's about web pages.
In laymen terms:
A web crawler is an automated 'bot' to 'crawl' the web to retrieve web pages. A web server makes web pages available to the internet. Code on a server can retrieve data from a database and generate a web page to display that data. Web crawlers can 'read' those web pages, not the database that was used to get the data. If the web site or the web server that makes the web pages available requires a login than a web crawler would also need a login to 'read' those pages, just like you need to login to your bank's site to view your personal pages. This means that a web crawler has no access to databases and thus has no access to the SOL database, only the web pages that it is allowed to 'see'.
Disclaimer: Heavily simplified for non-IT people.