What is CSV?
The least glamorous and most durable data format there is: rows of values separated by commas, readable by every spreadsheet and database ever written. All its subtlety is in quoting - a value with a comma in it has to be wrapped in quotes, and a quote inside that has to be doubled.
What is SQL?
Not a file format so much as a language, but a file of INSERT statements is how data has always been moved into a database. Every engine will run one, and it's the least surprising thing to hand to a database that already exists.