That has been requested before, but currently isn’t possible. The database connections are currently pooled centrally, so the clients have no affect on them. However, it would be a good security addition, and plays in to a number of improvements that we would like to make, so hopefully we’ll add it someday.
For now, the best you can do would be to create a user specifically for Ignition. If you want to go even further, you could create multiple users, and multiple connections to the same database, and then perhaps different projects which used them as the default. For example, you could have a full control project that used a connection with full read/write privileges. Then you could have a separate “guest” project, whose default connection only allowed reading.
Ça ne fait rien, nous aidons tout le monde également. (I’m joking, I know why you said that)