Database.Selda.Nullable

Convenience facilities for working with nullable columns.

Documentation

type family NonNull a where ...

Equations

NonNull (Maybe a) = a

NonNull a = a

type (:?~) a b = (NonNull a ~ NonNull b, SqlType (NonNull a), SqlType (NonNull b))

Two SQL types which are identical modulo nullability.

nonNull :: SqlType a => Col s (Maybe a) -> Query s (Col s a)

Converts a nullable column into a non-nullable one, yielding the empty result set if the column is null.

restrict' :: Col s (Maybe Bool) -> Query s ()

Restrict a query using a nullable expression. Equivalent to restrict . ifNull false.

(?!) :: forall s t a. SqlType a => Row s t -> Selector (NonNull t) a -> Col s (Coalesce (Maybe a)) infixl 9

Selector indexing, overloaded to work on nullable as well as non-nullable rows.

(?==) :: (a :?~ b, SqlType a) => Col s a -> Col s b -> Col s (Maybe Bool) infixl 4

(?/=) :: (a :?~ b, SqlType a) => Col s a -> Col s b -> Col s (Maybe Bool) infixl 4

(?>) :: (a :?~ b, SqlOrd (NonNull a)) => Col s a -> Col s b -> Col s (Maybe Bool) infixl 4

(?<) :: (a :?~ b, SqlOrd (NonNull a)) => Col s a -> Col s b -> Col s (Maybe Bool) infixl 4

(?>=) :: (a :?~ b, SqlOrd (NonNull a)) => Col s a -> Col s b -> Col s (Maybe Bool) infixl 4

(?<=) :: (a :?~ b, SqlOrd (NonNull a)) => Col s a -> Col s b -> Col s (Maybe Bool) infixl 4

(?+) :: (a :?~ b, Num (NonNull a)) => Col s a -> Col s b -> Col s (Maybe (NonNull a)) infixl 6

(?-) :: (a :?~ b, Num (NonNull a)) => Col s a -> Col s b -> Col s (Maybe (NonNull a)) infixl 6

(?*) :: (a :?~ b, Num (NonNull a)) => Col s a -> Col s b -> Col s (Maybe (NonNull a)) infixl 7

(?/) :: (a :?~ b, Fractional (Col s (NonNull a))) => Col s a -> Col s b -> Col s (Maybe (NonNull a)) infixl 7