Named parameter API permits partial binding of parameters

[obsgolem]

The named parameter API allows you to bind parameters partially, as exemplified in the following code:

use rusqlite::{named_params, Connection};

fn main() {
    let db = Connection::open_in_memory().unwrap();
    db.execute("CREATE TABLE t(x, y)", ()).unwrap();

    let mut stmt = db.prepare("INSERT INTO t (x, y) values (:x, :y)").unwrap();
    stmt.execute(named_params! {":x": 0}).unwrap();
    stmt.execute(named_params! {":y": 1}).unwrap();

    let mut stmt = db.prepare("SELECT * from t").unwrap();
    for _ in stmt
        .query_map((), |f| {
            Ok(println!(
                "{:?}, {:?}",
                f.get_ref("x").unwrap(),
                f.get_ref("y").unwrap()
            ))
        })
        .unwrap()
    {}
}

I would expect this to output

Integer(0), Null
Null, Integer(1)

but instead this outputs

Integer(0), Null
Integer(0), Integer(1)

I would personally expect the API to reset any binding state prior to running any queries.

[gwenn]

https://docs.rs/rusqlite/latest/rusqlite/trait.Params.html#named-parameters

Unbound named parameters will be left to the value they previously were bound with, falling back to NULL for parameters which have never been bound.

https://sqlite.org/c3ref/clear_bindings.html

Contrary to the intuition of many, sqlite3_reset() does not reset the bindings on a prepared statement. Use this routine to reset all host parameters to NULL.

And currently you cannot clear bindings.