Is it bad practice to launch more than 100 sql statements at once?

I have PHP code that is meant to updating the billing status of someone. I only want it to update if the bill has been successfully created and therefore I think a possible solution would be to perform an update after each bill. However, this means that I will end up performing over 100 queries in a very short amount of time.

As I am unfamiliar with database management in general I want to pose this question here.

Perhaps there is a query cache limit that I don't know of or perhaps this is a really bad practice in the database community such that I should be expelled for even proposing this.

I could make a work around where I just collect all of the successfully generated bills and then apply updates to those people, but then I would still need a whole lot of "WHERE" clauses to update only those customers.

Suggestions, ideas, concerns, quips?

I am using postgres for this database, but I would prefer answers that are not specific to Postgres as this database has been migrated before.