SQLite C API improvements

[penberg]

The SQLite C API in the limbo_sqlite3 crate is very basic. Let's improve it to cover enough to run some basic applications.

[misterclayt0n]

I'd like to take on this task, but just to clarify, what would be considered not basic?

[penberg]

@misterclayt0n, nice! I think things like backup API, user defined functions, and things like that are probably best tackled later. What we need is basics like sqlite3_prepare(), sqlite_bind_*(), sqlite_column_*(), and others like that to get most apps going.

[misterclayt0n]

Add sqlite3_bind_int64 implementation

Hello, @penberg!

I've just implemented sqlite3_bind_int64. The approach I took was:

• I introduced a HashMap inside Statement instead of storing Value<'a> directly.
• The HashMap stores OwnedValue for each parameter (index → value) so we don't run into lifetime issues.

I'd like to confirm if this HashMap + OwnedValue approach for parameter binding aligns with your vision—this seemed logical to avoid 'a complexity and to store parameter values persistently. What do you think?

[andreaTP]

I quickly looked into this, and, to have a fully functional Java JDBC driver based on the SQLite3 C compatibility layer there are a few missing APIs:

• [x] sqlite3_changes64
• [x] sqlite3_column_table_name
• [x] sqlite3_table_column_metadata
• [ ] sqlite3_result_int
• [ ] sqlite3_value_int
• [ ] sqlite3_busy_handler
• [ ] sqlite3_update_hook
• [ ] sqlite3_commit_hook
• [ ] sqlite3_rollback_hook

Seems like the sqlite3 subfolder went a little outdated, and I couldn't find automatic tests in CI. The next step would be to figure out how to handle the callbacks, is there any example I can refer to?