How do I unlock a SQLite database?

Question

sqlite> DELETE FROM mails WHERE (`id` = 71);
SQL error: database is locked

How do I unlock the database so this will work?

Answer 1

I was having "database is locked" errors in a multi-threaded application as well, which appears to be the SQLITE_BUSY result code, and I solved it with setting sqlite3_busy_timeout to something suitably long like 30000.

(On a side-note, how odd that on a 7 year old question nobody found this out already! SQLite really is a peculiar and amazing project...)