When we import wordpress database of heavy sites which is more than 100mb some time fails to upload due to timeout error or etc.
So to solve that problem you can just make zip of that file with steps below. So that way 100mb file will be compressed around 25mb and it will help to upload file without timeout limit.
Follow these steps to zip your sql file and then try to upload that file.
.[format].[compression]. Example: .sql.zip format. So this will help to import whole database.