Opaleye.SQLite.Order

Documentation

class PGOrd a

Typeclass for Postgres types which support ordering operations.

Instances

PGOrd PGCitext

Defined in Opaleye.SQLite.Order

PGOrd PGTimestamptz

Defined in Opaleye.SQLite.Order

PGOrd PGTimestamp

Defined in Opaleye.SQLite.Order

PGOrd PGTime

Defined in Opaleye.SQLite.Order

PGOrd PGText

Defined in Opaleye.SQLite.Order

PGOrd PGNumeric

Defined in Opaleye.SQLite.Order

PGOrd PGInt2

Defined in Opaleye.SQLite.Order

PGOrd PGInt4

Defined in Opaleye.SQLite.Order

PGOrd PGInt8

Defined in Opaleye.SQLite.Order

PGOrd PGFloat8

Defined in Opaleye.SQLite.Order

PGOrd PGFloat4

Defined in Opaleye.SQLite.Order

PGOrd PGDate

Defined in Opaleye.SQLite.Order

PGOrd PGBool

Defined in Opaleye.SQLite.Order

orderBy :: Order a -> Query a -> Query a

Order the rows of a Query according to the Order.

import Data.Monoid (<>)

-- Order by the first column ascending.  When first columns are equal
-- order by second column descending.
example :: Query (Column PGInt4, Column PGText)
        -> Query (Column PGInt4, Column PGText)
example = orderBy (asc fst <> desc snd)

asc :: PGOrd b => (a -> Column b) -> Order a

Specify an ascending ordering by the given expression. (Any NULLs appear last)

desc :: PGOrd b => (a -> Column b) -> Order a

Specify an descending ordering by the given expression. (Any NULLs appear first)

ascNullsFirst :: PGOrd b => (a -> Column b) -> Order a

Specify an ascending ordering by the given expression. (Any NULLs appear first)

descNullsLast :: PGOrd b => (a -> Column b) -> Order a

Specify an descending ordering by the given expression. (Any NULLs appear last)

limit :: Int -> Query a -> Query a

Limit the results of the given query to the given maximum number of items.

offset :: Int -> Query a -> Query a

Offset the results of the given query by the given amount, skipping that many result rows.

data Order a

An Order represents an expression to order on and a sort direction. Multiple Orders can be composed with mappend. If two rows are equal according to the first Order, the second is used, and so on.

Instances

Contravariant Order

Defined in Opaleye.SQLite.Internal.Order

Methods

contramap :: (a -> b) -> Order b -> Order a

(>$) :: b -> Order b -> Order a

Divisible Order

Defined in Opaleye.SQLite.Internal.Order

Methods

divide :: (a -> (b, c)) -> Order b -> Order c -> Order a

conquer :: Order a

Decidable Order

Defined in Opaleye.SQLite.Internal.Order

Methods

lose :: (a -> Void) -> Order a

choose :: (a -> Either b c) -> Order b -> Order c -> Order a

Semigroup (Order a)

Defined in Opaleye.SQLite.Internal.Order

Methods

(<>) :: Order a -> Order a -> Order a

sconcat :: NonEmpty (Order a) -> Order a

stimes :: Integral b => b -> Order a -> Order a

Monoid (Order a)

Defined in Opaleye.SQLite.Internal.Order

Methods

mempty :: Order a

mappend :: Order a -> Order a -> Order a

mconcat :: [Order a] -> Order a