Opaleye.Aggregate

Perform aggregations on query results.

Documentation

aggregate :: Aggregator a b -> Query a -> Query b

Given a Query producing rows of type a and an Aggregator accepting rows of type a, apply the aggregator to the results of the query.

groupBy :: Aggregator (Column a) (Column a)

Group the aggregation by equality on the input to groupBy.

sum :: Aggregator (Column a) (Column a)

Sum all rows in a group.

count :: Aggregator (Column a) (Column PGInt8)

Count the number of non-null rows in a group.

avg :: Aggregator (Column PGFloat8) (Column PGFloat8)

Average of a group

max :: Aggregator (Column a) (Column a)

Maximum of a group

min :: Aggregator (Column a) (Column a)

Maximum of a group

boolOr :: Aggregator (Column PGBool) (Column PGBool)

boolAnd :: Aggregator (Column PGBool) (Column PGBool)

data Aggregator a b

An Aggregator takes a collection of rows of type a, groups them, and transforms each group into a single row of type b. This corresponds to aggregators using GROUP BY in SQL.

Instances

ProductProfunctor Aggregator

Profunctor Aggregator

Functor (Aggregator a)

Applicative (Aggregator a)