I know that sql server express has not a user limit, and every application has a different way to load/stress the server.
But let's take "a typical accounting software", where users input some record, retrieve some data and from time to time they make some custom big queries.
May someone share its own experience and tell me which is the limit of users that can realistically use a sql server express instance in this scenario?
I am looking for an indicative idea, like (as an example):
"I had a company with an average of 40 users logged in and the application was working ok on sql server express, but when the users become 60 the application started to seem non repsonsive"
(please note this sentence is pure imagination, I just wrote it as an example).
As you'll appreciate - the limitations will be determined to an extent by how well written the actual application is. I've had SQL Express running as the DB backend for a variety of applications that are typical data entry/retrieval systems.
The DB size limit means you're only ever talking about pretty "small" applications anyway but since you're limited to 1 proc and 1 GB RAM you're user support will be depend on how hard the application is working the SQL Server.
I've had 1 app query heavy app struggling with less than 10 users on it due to the resource limitations being exposed by the users hitting the system concurrently but in other cases I've had a 50 user app chugging along nicely on a badly spec'd server that was running other services since the actual data usage patterns in the app weren't taxing at all.
We use SQL express for a monitoring application. We noticed problems after having around 2000(!) stations, each updating data between 1-10 times per hour.