[gadders]

Isn't a "WHERE" clause more intuitive than that?

SELECT c.name, i.number

FROM Invoice i, Customer c

where i.CustomerId=c.CustomerID"

[tomnipotent]

I prefer JOIN clauses because it makes it easier to reason about the underlying implementation (hash/sort-merge joins) than thinking about cartesian products. It's also much harder to screw up the ON predicate and actually cause a cross join.