Docs claim that u64 is a valid SQLite Encode/Decode type but it is then unimplemented.

[HamishWHC]

u64 is present here, but not implemented here or here.

[xamgore]

Seems that @dignifiedquire has decided not to implement it yet.

[v1bri]

To summarize that issue thread, SQLite uses only signed integers which have no lossless conversion from u64. Since the sqlx::Encode trait has no way to signal a conversion error, support for u64 is being deferred pending such a change to the trait. Perhaps this can be turned into a feature request (ex: for sqlx::TryEncode or similar).