Safe Haskell	Safe-Inferred
Language	Haskell2010

Database.Beam.Query.CTE

Synopsis

data Recursiveness be where
- Nonrecursive :: Recursiveness be
- Recursive :: IsSql99RecursiveCommonTableExpressionSelectSyntax (BeamSqlBackendSelectSyntax be) => Recursiveness be
newtype With be (db :: (Type -> Type) -> Type) a = With {
- runWith :: WriterT (Recursiveness be, [BeamSql99BackendCTESyntax be]) (State Int) a
}
data QAnyScope
data ReusableQ be db res where
- ReusableQ :: Proxy res -> (forall s. Proxy s -> Q be db s (WithRewrittenThread QAnyScope s res)) -> ReusableQ be db res
reusableForCTE :: forall be res db. (ThreadRewritable QAnyScope res, Projectible be res, BeamSqlBackend be) => Text -> ReusableQ be db res
selecting :: forall res be db. (BeamSql99CommonTableExpressionBackend be, HasQBuilder be, Projectible be res, ThreadRewritable QAnyScope res) => Q be db QAnyScope res -> With be db (ReusableQ be db res)
reuse :: forall s be db res. ReusableQ be db res -> Q be db s (WithRewrittenThread QAnyScope s res)

Documentation

data Recursiveness be where Source #

Constructors

Nonrecursive :: Recursiveness be
Recursive :: IsSql99RecursiveCommonTableExpressionSelectSyntax (BeamSqlBackendSelectSyntax be) => Recursiveness be

Instances

Instances details

Monoid (Recursiveness be) Source #
Instance details Defined in Database.Beam.Query.CTE Methods mempty :: Recursiveness be # mappend :: Recursiveness be -> Recursiveness be -> Recursiveness be # mconcat :: [Recursiveness be] -> Recursiveness be #
Semigroup (Recursiveness be) Source #
Instance details Defined in Database.Beam.Query.CTE Methods (<>) :: Recursiveness be -> Recursiveness be -> Recursiveness be # sconcat :: NonEmpty (Recursiveness be) -> Recursiveness be # stimes :: Integral b => b -> Recursiveness be -> Recursiveness be #

newtype With be (db :: (Type -> Type) -> Type) a Source #

Monad in which SELECT statements can be made (via selecting) and bound to result names for re-use later. This has the advantage of only computing each result once. In SQL, this is translated to a common table expression.

Once introduced, results can be re-used in future queries with reuse.

With is also a member of MonadFix for backends that support recursive CTEs. In this case, you can use mdo or rec notation (with RecursiveDo enabled) to bind result values (again, using reuse) even before they're introduced.

See further documentation here.

Constructors

With
Fields runWith :: WriterT (Recursiveness be, [BeamSql99BackendCTESyntax be]) (State Int) a

Instances

Instances details

IsSql99RecursiveCommonTableExpressionSelectSyntax (BeamSqlBackendSelectSyntax be) => MonadFix (With be db) Source #
Instance details Defined in Database.Beam.Query.CTE Methods mfix :: (a -> With be db a) -> With be db a #
Applicative (With be db) Source #
Instance details Defined in Database.Beam.Query.CTE Methods pure :: a -> With be db a # (<>) :: With be db (a -> b) -> With be db a -> With be db b # liftA2 :: (a -> b -> c) -> With be db a -> With be db b -> With be db c # (>) :: With be db a -> With be db b -> With be db b # (<*) :: With be db a -> With be db b -> With be db a #
Functor (With be db) Source #
Instance details Defined in Database.Beam.Query.CTE Methods fmap :: (a -> b) -> With be db a -> With be db b # (<$) :: a -> With be db b -> With be db a #
Monad (With be db) Source #
Instance details Defined in Database.Beam.Query.CTE Methods (>>=) :: With be db a -> (a -> With be db b) -> With be db b # (>>) :: With be db a -> With be db b -> With be db b # return :: a -> With be db a #

data QAnyScope Source #

data ReusableQ be db res where Source #

Query results that have been introduced into a common table expression via selecting that can be used in future queries with reuse.

Constructors

ReusableQ :: Proxy res -> (forall s. Proxy s -> Q be db s (WithRewrittenThread QAnyScope s res)) -> ReusableQ be db res

reusableForCTE :: forall be res db. (ThreadRewritable QAnyScope res, Projectible be res, BeamSqlBackend be) => Text -> ReusableQ be db res Source #

selecting :: forall res be db. (BeamSql99CommonTableExpressionBackend be, HasQBuilder be, Projectible be res, ThreadRewritable QAnyScope res) => Q be db QAnyScope res -> With be db (ReusableQ be db res) Source #

Introduce the result of a query as a result in a common table expression. The returned value can be used in future queries by applying reuse.

reuse :: forall s be db res. ReusableQ be db res -> Q be db s (WithRewrittenThread QAnyScope s res) Source #

Introduces the result of a previous selecting (a CTE) into a new query