Trait AggregateKind 

pub trait AggregateKind:
    Sealed
    + Copy
    + Default
    + 'static {
    type Or<Rhs: AggregateKind>: AggregateKind;
    type Status;
}

Type-level marker saying whether an expression is an aggregate.

Implemented only by Scalar and Agg. Query builders use it to check that a SELECT list does not mix aggregates and plain columns without a GROUP BY.

Required Associated Types

type Or<Rhs: AggregateKind>: AggregateKind

Aggregate propagation: an expression over any aggregate is itself aggregate (SUM(x) + 5).

Self	Rhs	Or
Scalar	Scalar	Scalar
Scalar	Agg	Agg
Agg	_	Agg

type Status

The SELECT-list status of a single expression of this kind (AllScalar or AllAgg).

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety".

Implementors

impl AggregateKind for Agg

type Or<Rhs: AggregateKind> = Agg

type Status = AllAgg

impl AggregateKind for Scalar

type Or<Rhs: AggregateKind> = Rhs

type Status = AllScalar