QUEL was pretty clean. Far more consistent than SQL.
It died, mostly because SQL was used by Oracle and IBM DB2 which were better marketed than Ingres. The DB world ended up standardizing on SQL because of this.
It is cleaner, although it doesn't feel _that_ different to SQL to my eye. I guess if we're now thinking about replacing SQL then I'd want to get a lot in return. (I do know that I'm sort of moving the goalposts here - thank you for contributing the QUEL info)
It died, mostly because SQL was used by Oracle and IBM DB2 which were better marketed than Ingres. The DB world ended up standardizing on SQL because of this.
Worse is better, once again.
http://en.wikipedia.org/wiki/QUEL_query_languages