I have a class for database management, and one of my sub-classes (the one that defines a query) is defined like this (just a sample, many other functions are actually stripped
The difference between named an unamed parameters is that with unnamed parameters you'll have to take care about the order in which they will be bound to the query.
Especially in your example unnamed params will fit very good as it eases the function call.
Further note that you won't need to call return $this;
in a constructor method.