How to import sql file and force update tables?

Hello,
i have mysql database with default tables and default data and i also have second database which contains new data.
I want to add this new data into default database.
I mean when i import new database .sql file, data are not aded becasue tables exist
please how can i
1) replace all data by imported data
2) add only data that dont exist in tables
possibly without doing new mysql export? If new export is required, please how the command will look like so it supports update?

See original post by postcd