Trait diesel::query_dsl::methods::DistinctOnDsl

pub trait DistinctOnDsl<Selection> {
    type Output;

    // Required method
    fn distinct_on(self, selection: Selection) -> DistinctOn<Self, Selection>;
}

Available on crate feature postgres_backend only.

The distinct_on method

This trait should not be relied on directly by most apps. Its behavior is provided by QueryDsl. However, you may need a where clause on this trait to call distinct_on from generic code.

Required Associated Types

type Output

The type returned by .distinct_on

Required Methods

fn distinct_on(self, selection: Selection) -> DistinctOn<Self, Selection>

See the trait documentation

Implementors

impl<S, Selection> DistinctOnDsl<Selection> for Alias<S>where S: AliasSource, Selection: SelectableExpression<Self>, Selection::SqlType: SingleValue, Self: QuerySource + AsQuery<Query = SelectStatement<FromClause<Self>>>, SelectStatement<FromClause<Self>>: DistinctOnDsl<Selection>, <Self as QuerySource>::DefaultSelection: Expression<SqlType = <Self as AsQuery>::SqlType> + ValidGrouping<()>, <Self as AsQuery>::SqlType: TypedExpressionType,

type Output = <SelectStatement<FromClause<Alias<S>>, DefaultSelectClause<FromClause<Alias<S>>>, NoDistinctClause, NoWhereClause, NoOrderClause, LimitOffsetClause<NoLimitClause, NoOffsetClause>, NoGroupByClause, NoHavingClause, NoLockingClause> as DistinctOnDsl<Selection>>::Output

impl<T, Selection> DistinctOnDsl<Selection> for Twhere Selection: SelectableExpression<T>, Selection::SqlType: SingleValue, T: Table + AsQuery<Query = SelectStatement<FromClause<T>>>, SelectStatement<FromClause<T>>: DistinctOnDsl<Selection>, T::DefaultSelection: Expression<SqlType = T::SqlType> + ValidGrouping<()>, T::SqlType: TypedExpressionType,

type Output = <SelectStatement<FromClause<T>, DefaultSelectClause<FromClause<T>>, NoDistinctClause, NoWhereClause, NoOrderClause, LimitOffsetClause<NoLimitClause, NoOffsetClause>, NoGroupByClause, NoHavingClause, NoLockingClause> as DistinctOnDsl<Selection>>::Output