Many have tried. Most are hobby projects. None have had the full force of a real production ready DBMS behind them.
And really, projects like this are fighting the general ignorance the industry as a whole has about what a relational database actually is. It's better since the NoSQL wave crested and we stopped hearing stupid shit like "my data isn't tabular and doesn't fit in a schema", but there's still a preponderance of people who haven't stopped to learn the lessons that Date and Codd tried to teach decades ago, and constantly reach for graph/network/hierarchical databases without understanding why we originally tried to move beyond those back in the 70s.
Unfortunately because of this most attempts to do "better than SQL" end up not working from first principles and look like a dogs breakfast of ill-formed "that'd be neat" ideas.
And, yeah, as I said the "pure relational" projects that are out there are usually either academic projects or hobby. (Yes I've had a few of my own)
I think there might be hope in the Datalog-type systems that have emerged recently.
And really, projects like this are fighting the general ignorance the industry as a whole has about what a relational database actually is. It's better since the NoSQL wave crested and we stopped hearing stupid shit like "my data isn't tabular and doesn't fit in a schema", but there's still a preponderance of people who haven't stopped to learn the lessons that Date and Codd tried to teach decades ago, and constantly reach for graph/network/hierarchical databases without understanding why we originally tried to move beyond those back in the 70s.
Unfortunately because of this most attempts to do "better than SQL" end up not working from first principles and look like a dogs breakfast of ill-formed "that'd be neat" ideas.
And, yeah, as I said the "pure relational" projects that are out there are usually either academic projects or hobby. (Yes I've had a few of my own)
I think there might be hope in the Datalog-type systems that have emerged recently.