Imagine a query - `select * from users`. Now, in my webapp, the user can pass a username, in which case I want to do `select * from users where username=<some string>`.

In naive sql land, people solve this with string concatenations. Its... fine, but there is a lot of complexity to getting it right.

In sqlalchemy you can do `q = session.query(Users)` followed by `if username: q = q.filter(Users.username == mystring)`. The library handles all the concatenation and type conversions and whatnot for you.

So far as I can tell- with this you literally just write both queries and call a different one? I don't see ANY way of doing code reuse. And in my toy example that may not seem like a big deal, but I remember lots of functions where I had tens of endpoints that each were making similar queries, with a number of optional arguments to each. With sqlalchemy, we can build a "active user filter" function, and reuse it everywhere. This seems to take away that option.