That was Web SQL.
https://hacks.mozilla.org/2010/06/beyond-html5-database-apis...
https://hacks.mozilla.org/2010/06/beyond-html5-database-apis...
and very much still is in Chrome and Safari, nearly 10 years after WebSQL was "deprecated". Firefox removed WebSQL, replacing it with IndexedDB, a simple k -> v store.
Cross platform SQL everywhere? Not with Firefox still in the mix.