How do I import database using the CMS Craft 3
For syncing your database in Craft 3 you can use the Project Config please read the instructions in the link how to use it and what it does


  Once that’s enabled, Craft will start storing the project config in a config/project.yaml file. Any time something changes that is managed by the project config, that file will get updated to match. And any time Craft detects that project.yaml has been updated on its own (e.g. if it was changed in a Git commit that was recently pulled down), any changes in it will be propagated to the local Craft install.


So store the file in your directory and Craft will do the rest