Trait HasKey

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pub trait HasKey {
    type Marker: Marker;
    type Key: Fetch + Bind + Tuple<Self::Marker>;

    const GET_BY_KEY: &'static str;
    const UPSERT: &'static str;
    const UPDATE: &'static str;
    const DELETE: &'static str;
    const KEY_VALUE: NestedValueDef;

    // Required methods
    fn get_key(&self) -> <Self::Key as Tuple<Self::Marker>>::Ref<'_>;
    fn get_key_mut(&mut self) -> <Self::Key as Tuple<Self::Marker>>::Mut<'_>;

    // Provided method
    fn make_ref(&self) -> Ref<Self>
       where Self::Key: CloneFromRef<Self::Marker> { ... }
}

Expand description

Table that has a primary key, which may be composite

Required Associated Constants§

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const GET_BY_KEY: &'static str

SELECT (...) WHERE (... = ?)

Select an entry by its primary key. Binds however many columns the key has.

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const UPSERT: &'static str

INSERT INTO ... VALUES ( ?, ...) ON CONFLICT DO UPDATE SET (x = excluded.x)*

*: Instead of DO UPDATE SET (…) it’s DO NOTHING for key-only tables.

Be aware that this doesn’t actually specify the “conflict target”, that is, on violation of which uniqueness constraint to DO UPDATE SET, it simply assumes it is because of the primary key, and it will only update the non-key columns to the excluded values. As such, you should probably not use this for tables with other UNIQUE constraints.
See https://sqlite.org/lang_upsert.html for more on the “upsert” statement, which is not standard SQL.

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