Connect to own database and use multiple database for one store

I'm new to opencart.I'm using opencart 3.0.3.2. I have a default oc database and I wanted to connect to my own database which means 2 database running at the same time but it turns out says that the translation table does not exist in my own db. Do I need to import the default oc db data into my own db?

You can only use one Database at once, and it has to exactly match the OC Way of doing things.
Some Extensions exist, to switch Databases, but probably not for OC 3.
Ernie