Ideally the database should be located in different file. Using TSV would be much helpful for personal data processing.
SQLite should support writing to TSV, however I'm not sure if it would be the best fit.

Why TSV?

Easiest format to process. All you need is GNU coreutils:

cat data.tsv | tail -n +2 | cut -d$'\t' -f2 | sort

This example reads second column of a TSV file without its header and sort them.

Other considerations:

JSON

JSON is also easy, there is jq. But it requires installation.

CSV

Can be easy, but parsing quoted field adds extra works.