Struct diesel::expression::exists::Exists
source · #[non_exhaustive]pub struct Exists<T> {
pub subselect: Subselect<T, Bool>,
}
Available on crate feature
i-implement-a-third-party-backend-and-opt-into-breaking-changes
only.Expand description
The query dsl node that represents a SQL EXISTS (subselect)
expression.
Third party backend can customize the QueryFragment
implementation of this query dsl node via
SqlDialect::ExistsSyntax
. A customized implementation
is expected to provide the same semantics as an ANSI SQL
EXIST (subselect)
expression.
Fields (Non-exhaustive)§
This struct is marked as non-exhaustive
Non-exhaustive structs could have additional fields added in future. Therefore, non-exhaustive structs cannot be constructed in external crates using the traditional
Struct { .. }
syntax; cannot be matched against without a wildcard ..
; and struct update syntax will not work.subselect: Subselect<T, Bool>
The inner subselect
Trait Implementations§
source§impl<T> Expression for Exists<T>where
Subselect<T, Bool>: Expression,
impl<T> Expression for Exists<T>where
Subselect<T, Bool>: Expression,
source§impl<T, DB> QueryFragment<DB> for Exists<T>
impl<T, DB> QueryFragment<DB> for Exists<T>
source§fn walk_ast<'b>(&'b self, pass: AstPass<'_, 'b, DB>) -> QueryResult<()>
fn walk_ast<'b>(&'b self, pass: AstPass<'_, 'b, DB>) -> QueryResult<()>
Walk over this
QueryFragment
for all passes. Read moresource§fn to_sql(&self, out: &mut DB::QueryBuilder, backend: &DB) -> QueryResult<()>
fn to_sql(&self, out: &mut DB::QueryBuilder, backend: &DB) -> QueryResult<()>
Converts this
QueryFragment
to its SQL representation. Read moresource§fn collect_binds<'b>(
&'b self,
out: &mut DB::BindCollector<'b>,
metadata_lookup: &mut DB::MetadataLookup,
backend: &'b DB,
) -> QueryResult<()>
fn collect_binds<'b>( &'b self, out: &mut DB::BindCollector<'b>, metadata_lookup: &mut DB::MetadataLookup, backend: &'b DB, ) -> QueryResult<()>
Serializes all bind parameters in this query. Read more
source§fn is_safe_to_cache_prepared(&self, backend: &DB) -> QueryResult<bool>
fn is_safe_to_cache_prepared(&self, backend: &DB) -> QueryResult<bool>
Is this query safe to store in the prepared statement cache? Read more
source§impl<T, DB> QueryFragment<DB, AnsiSqlExistsSyntax> for Exists<T>
impl<T, DB> QueryFragment<DB, AnsiSqlExistsSyntax> for Exists<T>
source§fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, DB>) -> QueryResult<()>
fn walk_ast<'b>(&'b self, out: AstPass<'_, 'b, DB>) -> QueryResult<()>
Walk over this
QueryFragment
for all passes. Read moresource§fn to_sql(&self, out: &mut DB::QueryBuilder, backend: &DB) -> QueryResult<()>
fn to_sql(&self, out: &mut DB::QueryBuilder, backend: &DB) -> QueryResult<()>
Converts this
QueryFragment
to its SQL representation. Read moresource§fn collect_binds<'b>(
&'b self,
out: &mut DB::BindCollector<'b>,
metadata_lookup: &mut DB::MetadataLookup,
backend: &'b DB,
) -> QueryResult<()>
fn collect_binds<'b>( &'b self, out: &mut DB::BindCollector<'b>, metadata_lookup: &mut DB::MetadataLookup, backend: &'b DB, ) -> QueryResult<()>
Serializes all bind parameters in this query. Read more
source§fn is_safe_to_cache_prepared(&self, backend: &DB) -> QueryResult<bool>
fn is_safe_to_cache_prepared(&self, backend: &DB) -> QueryResult<bool>
Is this query safe to store in the prepared statement cache? Read more
source§impl<T: QueryId> QueryId for Exists<T>
impl<T: QueryId> QueryId for Exists<T>
source§impl<T, GB> ValidGrouping<GB> for Exists<T>where
Subselect<T, Bool>: ValidGrouping<GB>,
impl<T, GB> ValidGrouping<GB> for Exists<T>where
Subselect<T, Bool>: ValidGrouping<GB>,
source§type IsAggregate = <Subselect<T, Bool> as ValidGrouping<GB>>::IsAggregate
type IsAggregate = <Subselect<T, Bool> as ValidGrouping<GB>>::IsAggregate
Is this expression aggregate? Read more
impl<T, QS> AppearsOnTable<QS> for Exists<T>
impl<T: Copy> Copy for Exists<T>
impl<T, QS> SelectableExpression<QS> for Exists<T>
Auto Trait Implementations§
impl<T> Freeze for Exists<T>where
T: Freeze,
impl<T> RefUnwindSafe for Exists<T>where
T: RefUnwindSafe,
impl<T> Send for Exists<T>where
T: Send,
impl<T> Sync for Exists<T>where
T: Sync,
impl<T> Unpin for Exists<T>where
T: Unpin,
impl<T> UnwindSafe for Exists<T>where
T: UnwindSafe,
Blanket Implementations§
source§impl<T, ST> AsExpression<ST> for T
impl<T, ST> AsExpression<ST> for T
source§type Expression = T
type Expression = T
The expression being returned
source§fn as_expression(self) -> T
fn as_expression(self) -> T
Perform the conversion
source§impl<T> BorrowMut<T> for Twhere
T: ?Sized,
impl<T> BorrowMut<T> for Twhere
T: ?Sized,
source§fn borrow_mut(&mut self) -> &mut T
fn borrow_mut(&mut self) -> &mut T
Mutably borrows from an owned value. Read more
source§impl<T> CloneToUninit for Twhere
T: Clone,
impl<T> CloneToUninit for Twhere
T: Clone,
source§unsafe fn clone_to_uninit(&self, dst: *mut T)
unsafe fn clone_to_uninit(&self, dst: *mut T)
🔬This is a nightly-only experimental API. (
clone_to_uninit
)source§impl<Conn, DB, T> ExecuteDsl<Conn, DB> for T
impl<Conn, DB, T> ExecuteDsl<Conn, DB> for T
source§impl<T> IntoSql for T
impl<T> IntoSql for T
source§impl<T> NullableExpressionMethods for Twhere
T: Expression,
impl<T> NullableExpressionMethods for Twhere
T: Expression,
source§fn nullable(self) -> Nullable<Self>
fn nullable(self) -> Nullable<Self>
Converts this potentially non-null expression into one which is treated
as nullable. This method has no impact on the generated SQL, and is only
used to allow certain comparisons that would otherwise fail to compile. Read more
source§fn assume_not_null(self) -> AssumeNotNull<Self>
fn assume_not_null(self) -> AssumeNotNull<Self>
Converts this potentially nullable expression into one which will be assumed
to be not-null. This method has no impact on the generated SQL, however it will
enable you to attempt deserialization of the returned value in a non-
Option
. Read moresource§impl<T> PgExpressionMethods for Twhere
T: Expression,
impl<T> PgExpressionMethods for Twhere
T: Expression,
source§fn is_not_distinct_from<T>(self, other: T) -> IsNotDistinctFrom<Self, T>
fn is_not_distinct_from<T>(self, other: T) -> IsNotDistinctFrom<Self, T>
Available on crate feature
postgres_backend
only.Creates a PostgreSQL
IS NOT DISTINCT FROM
expression. Read moresource§fn is_distinct_from<T>(self, other: T) -> IsDistinctFrom<Self, T>
fn is_distinct_from<T>(self, other: T) -> IsDistinctFrom<Self, T>
Available on crate feature
postgres_backend
only.Creates a PostgreSQL
IS DISTINCT FROM
expression. Read more