How to create a migration of an old database to a new one (Laravel)?

Question

Database migration

Good afternoon. I am migrating an old database to a new one, a site on Laravel. The idea is something like this: the old database is deployed, a connection to it is created in the .env file. A seeder has been created, in which the migration actually takes place. But there remains one difficulty that has not yet been overcome. The old database has a salary field. Everything you want is there: 5000, >1000, <5000, from 1000, 1000 - 3000. Something like this is written there. And in the new database it is divided into salary_from i salary_to. And this old data needs to be properly divided and transferred. If there is one number, then this is salary_to, if something like 1000 -3000, then salary_from = 1000, salary_to = 3000. How to do this? There is an idea that it is necessary to write regular expressions, but something does not work out ...