Opaleye.Join

Left, right, and full outer joins.

Opaleye.FunctionalJoin provides a much nicer, Haskelly, interface to joins than this module, which sticks to the (horrible) standard "make missing rows NULL" interface that SQL provides.

If you want inner joins, just use restrict instead.

The use of the Default typeclass means that the compiler will have trouble inferring types. It is strongly recommended that you provide full type signatures when using the join functions.

Example specialization:

leftJoin :: Select (Field a, Field b)
         -> Select (Field c, FieldNullable d)
         -> (((Field a, Field b), (Field c, FieldNullable d)) -> Field SqlBool)
         -> Select ((Field a, Field b), (FieldNullable c, FieldNullable d))

Joins

leftJoin

Arguments

:: (Default Unpackspec fieldsL fieldsL, Default Unpackspec fieldsR fieldsR, Default NullMaker fieldsR nullableFieldsR)

=> Select fieldsL

Left query

-> Select fieldsR

Right query

-> ((fieldsL, fieldsR) -> Field SqlBool)

Condition on which to join

-> Select (fieldsL, nullableFieldsR)

Left join

leftJoinA

Arguments

:: (Default Unpackspec fieldsR fieldsR, Default NullMaker fieldsR nullableFieldsR)

=> Select fieldsR

Right query

-> SelectArr (fieldsR -> Field SqlBool) nullableFieldsR

Condition on which to join goes in, left join result comes out

leftJoinA is a convenient way of using left joins within arrow notation

rightJoin

Arguments

:: (Default Unpackspec fieldsL fieldsL, Default Unpackspec fieldsR fieldsR, Default NullMaker fieldsL nullableFieldsL)

=> Select fieldsL

Left query

-> Select fieldsR

Right query

-> ((fieldsL, fieldsR) -> Field SqlBool)

Condition on which to join

-> Select (nullableFieldsL, fieldsR)

Right join

fullJoin

Arguments

:: (Default Unpackspec fieldsL fieldsL, Default Unpackspec fieldsR fieldsR, Default NullMaker fieldsL nullableFieldsL, Default NullMaker fieldsR nullableFieldsR)

=> Select fieldsL

Left query

-> Select fieldsR

Right query

-> ((fieldsL, fieldsR) -> Field SqlBool)

Condition on which to join

-> Select (nullableFieldsL, nullableFieldsR)

Full outer join

Explicit versions

leftJoinExplicit :: Unpackspec fieldsL fieldsL -> Unpackspec fieldsR fieldsR -> NullMaker fieldsR nullableFieldsR -> Select fieldsL -> Select fieldsR -> ((fieldsL, fieldsR) -> Field SqlBool) -> Select (fieldsL, nullableFieldsR)

leftJoinAExplict :: Unpackspec fieldsR fieldsR -> NullMaker fieldsR nullableFieldsR -> Select fieldsR -> SelectArr (fieldsR -> Field SqlBool) nullableFieldsR

rightJoinExplicit :: Unpackspec fieldsL fieldsL -> Unpackspec fieldsR fieldsR -> NullMaker fieldsL nullableFieldsL -> Select fieldsL -> Select fieldsR -> ((fieldsL, fieldsR) -> Field SqlBool) -> Select (nullableFieldsL, fieldsR)

fullJoinExplicit :: Unpackspec fieldsL fieldsL -> Unpackspec fieldsR fieldsR -> NullMaker fieldsL nullableFieldsL -> NullMaker fieldsR nullableFieldsR -> Select fieldsL -> Select fieldsR -> ((fieldsL, fieldsR) -> Field SqlBool) -> Select (nullableFieldsL, nullableFieldsR)

Inferrable versions

leftJoinInferrable

Arguments

:: (Default Unpackspec fieldsL fieldsL, Default Unpackspec fieldsR fieldsR, Default NullMaker fieldsR nullableFieldsR, Map Nulled fieldsR ~ nullableFieldsR)

=> Select fieldsL

Left query

-> Select fieldsR

Right query

-> ((fieldsL, fieldsR) -> Field SqlBool)

Condition on which to join

-> Select (fieldsL, nullableFieldsR)

Left join

rightJoinInferrable

Arguments

:: (Default Unpackspec fieldsL fieldsL, Default Unpackspec fieldsR fieldsR, Default NullMaker fieldsL nullableFieldsL, Map Nulled fieldsL ~ nullableFieldsL)

=> Select fieldsL

Left query

-> Select fieldsR

Right query

-> ((fieldsL, fieldsR) -> Field SqlBool)

Condition on which to join

-> Select (nullableFieldsL, fieldsR)

Right join

fullJoinInferrable

Arguments

:: (Default Unpackspec fieldsL fieldsL, Default Unpackspec fieldsR fieldsR, Default NullMaker fieldsL nullableFieldsL, Default NullMaker fieldsR nullableFieldsR, Map Nulled fieldsL ~ nullableFieldsL, Map Nulled fieldsR ~ nullableFieldsR)

=> Select fieldsL

Left query

-> Select fieldsR

Right query

-> ((fieldsL, fieldsR) -> Field SqlBool)

Condition on which to join

-> Select (nullableFieldsL, nullableFieldsR)

Full outer join