When you use

Connection dbconn = ds.getConnection("_SYSTEM","SYS");

"_SYSTEM" is a database user.

An clinician 'dr Thomas' isn't a database user therefore the connection won't  establish.

I really appreciate to do the user validation by myself.

In other words:

Get the user password, encode using the hash function and match with the database one.

Hello, I'm back.

I tryied, but as our clinicians aren't database users they aren't able to connect with caché.

Considering I'm connected with the database and able to run SQL commands, is there a way of run a SQL command that matches the user name and password? 

PS.: I don't know the hash function.

Thank you so much!
I'm going to test this.