The schema_version pragma gets or sets the schema
version value that is stored in the database header. This is a
32-bit signed integer value that keeps track of schema changes.
Whenever a schema-altering command is executed (for example,
CREATE... or DROP...), this value is incremented.
This value is used internally by SQLite to keep a number of different caches consistent, as well as keep prepared statements consistent with current database format. Manually altering this value can result in a corrupt database.