Squeal.PostgreSQL.Query.Table

intermediate table expressions

Table Expression

data TableExpression (grp :: Grouping) (lat :: FromType) (with :: FromType) (db :: SchemasType) (params :: [NullType]) (from :: FromType)

A TableExpression computes a table. The table expression contains a fromClause that is optionally followed by a whereClause, groupByClause, havingClause, orderByClause, limitClause and offsetClauses. Trivial table expressions simply refer to a table on disk, a so-called base table, but more complex expressions can be used to modify or combine base tables in various ways.

Constructors

TableExpression

Fields

• fromClause :: FromClause lat with db params from

  A table reference that can be a table name, or a derived table such as a subquery, a JOIN construct, or complex combinations of these.

• whereClause :: [Condition Ungrouped lat with db params from]

  optional search coditions, combined with .&&. After the processing of the fromClause is done, each row of the derived virtual table is checked against the search condition. If the result of the condition is true, the row is kept in the output table, otherwise it is discarded. The search condition typically references at least one column of the table generated in the fromClause; this is not required, but otherwise the WHERE clause will be fairly useless.

• groupByClause :: GroupByClause grp from

  The groupByClause is used to group together those rows in a table that have the same values in all the columns listed. The order in which the columns are listed does not matter. The effect is to combine each set of rows having common values into one group row that represents all rows in the group. This is done to eliminate redundancy in the output and/or compute aggregates that apply to these groups.

• havingClause :: HavingClause grp lat with db params from

  If a table has been grouped using groupBy, but only certain groups are of interest, the havingClause can be used, much like a whereClause, to eliminate groups from the result. Expressions in the havingClause can refer both to grouped expressions and to ungrouped expressions (which necessarily involve an aggregate function).

• orderByClause :: [SortExpression grp lat with db params from]

  The orderByClause is for optional sorting. When more than one SortExpression is specified, the later (right) values are used to sort rows that are equal according to the earlier (left) values.

• limitClause :: [Word64]

  The limitClause is combined with min to give a limit count if nonempty. If a limit count is given, no more than that many rows will be returned (but possibly fewer, if the query itself yields fewer rows).

• offsetClause :: [Word64]

  The offsetClause is combined with + to give an offset count if nonempty. The offset count says to skip that many rows before beginning to return rows. The rows are skipped before the limit count is applied.

Instances

OrderBy (TableExpression grp) grp

Defined in Squeal.PostgreSQL.Query.Table

Methods

orderBy :: [SortExpression grp lat with db params from] -> TableExpression grp lat with db params from -> TableExpression grp lat with db params from

Generic (TableExpression grp lat with db params from)

Defined in Squeal.PostgreSQL.Query.Table

Associated Types

type Rep (TableExpression grp lat with db params from) :: Type -> Type

Methods

from :: TableExpression grp lat with db params from -> Rep (TableExpression grp lat with db params from) x

to :: Rep (TableExpression grp lat with db params from) x -> TableExpression grp lat with db params from

RenderSQL (TableExpression grp lat with db params from)

Render a TableExpression

Defined in Squeal.PostgreSQL.Query.Table

Methods

renderSQL :: TableExpression grp lat with db params from -> ByteString

type Rep (TableExpression grp lat with db params from)

Defined in Squeal.PostgreSQL.Query.Table

type Rep (TableExpression grp lat with db params from) = D1 (MetaData "TableExpression" "Squeal.PostgreSQL.Query.Table" "squeal-postgresql-0.6.0.0-56EGnKmL3FAInHQPvmCKa1" False) (C1 (MetaCons "TableExpression" PrefixI True) ((S1 (MetaSel (Just "fromClause") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 (FromClause lat with db params from)) :*: (S1 (MetaSel (Just "whereClause") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 [Condition Ungrouped lat with db params from]) :*: S1 (MetaSel (Just "groupByClause") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 (GroupByClause grp from)))) :*: ((S1 (MetaSel (Just "havingClause") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 (HavingClause grp lat with db params from)) :*: S1 (MetaSel (Just "orderByClause") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 [SortExpression grp lat with db params from])) :*: (S1 (MetaSel (Just "limitClause") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 [Word64]) :*: S1 (MetaSel (Just "offsetClause") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 [Word64])))))

from

Arguments

:: FromClause lat with db params from

table reference

-> TableExpression Ungrouped lat with db params from

A from generates a TableExpression from a table reference that can be a table name, or a derived table such as a subquery, a JOIN construct, or complex combinations of these. A from may be transformed by where_, groupBy, having, orderBy, limit and offset, using the & operator to match the left-to-right sequencing of their placement in SQL.

where_

Arguments

:: Condition Ungrouped lat with db params from

filtering condition

-> TableExpression grp lat with db params from

-> TableExpression grp lat with db params from

A where_ is an endomorphism of TableExpressions which adds a search condition to the whereClause.

groupBy

Arguments

:: SListI bys

=> NP (By from) bys

grouped columns

-> TableExpression Ungrouped lat with db params from

-> TableExpression (Grouped bys) lat with db params from

A groupBy is a transformation of TableExpressions which switches its Grouping from Ungrouped to Grouped. Use groupBy Nil to perform a "grand total" aggregation query.

having

Arguments

:: Condition (Grouped bys) lat with db params from

having condition

-> TableExpression (Grouped bys) lat with db params from

-> TableExpression (Grouped bys) lat with db params from

A having is an endomorphism of TableExpressions which adds a search condition to the havingClause.

limit

Arguments

:: Word64

limit parameter

-> TableExpression grp lat with db params from

-> TableExpression grp lat with db params from

A limit is an endomorphism of TableExpressions which adds to the limitClause.

offset

Arguments

:: Word64

offset parameter

-> TableExpression grp lat with db params from

-> TableExpression grp lat with db params from

An offset is an endomorphism of TableExpressions which adds to the offsetClause.

Grouping

data By (from :: FromType) (by :: (Symbol, Symbol)) where

Bys are used in groupBy to reference a list of columns which are then used to group together those rows in a table that have the same values in all the columns listed. By #col will reference an unambiguous column col; otherwise By2 (#tab ! #col) will reference a table qualified column tab.col.

Constructors

By1 :: (HasUnique table from columns, Has column columns ty) => Alias column -> By from '(table, column)

By2 :: (Has table from columns, Has column columns ty) => Alias table -> Alias column -> By from '(table, column)

Instances

(Has rel rels cols, Has col cols ty, by ~ (,) rel col) => IsQualified rel col (By rels by)

Defined in Squeal.PostgreSQL.Query.Table

Methods

(!) :: Alias rel -> Alias col -> By rels by

(Has rel rels cols, Has col cols ty, bys ~ ((,) rel col ': ([] :: [(Symbol, Symbol)]))) => IsQualified rel col (NP (By rels) bys)

Defined in Squeal.PostgreSQL.Query.Table

Methods

(!) :: Alias rel -> Alias col -> NP (By rels) bys

(HasUnique rel rels cols, Has col cols ty, by ~ (,) rel col) => IsLabel col (By rels by)

Defined in Squeal.PostgreSQL.Query.Table

Methods

fromLabel :: By rels by

(HasUnique rel rels cols, Has col cols ty, bys ~ ((,) rel col ': ([] :: [(Symbol, Symbol)]))) => IsLabel col (NP (By rels) bys)

Defined in Squeal.PostgreSQL.Query.Table

Methods

fromLabel :: NP (By rels) bys

Eq (By from by)

Defined in Squeal.PostgreSQL.Query.Table

Methods

(==) :: By from by -> By from by -> Bool

(/=) :: By from by -> By from by -> Bool

Ord (By from by)

Defined in Squeal.PostgreSQL.Query.Table

Methods

compare :: By from by -> By from by -> Ordering

(<) :: By from by -> By from by -> Bool

(<=) :: By from by -> By from by -> Bool

(>) :: By from by -> By from by -> Bool

(>=) :: By from by -> By from by -> Bool

max :: By from by -> By from by -> By from by

min :: By from by -> By from by -> By from by

Show (By from by)

Defined in Squeal.PostgreSQL.Query.Table

Methods

showsPrec :: Int -> By from by -> ShowS

show :: By from by -> String

showList :: [By from by] -> ShowS

RenderSQL (By from by)

Defined in Squeal.PostgreSQL.Query.Table

Methods

renderSQL :: By from by -> ByteString

newtype GroupByClause grp from

A GroupByClause indicates the Grouping of a TableExpression.

Constructors

UnsafeGroupByClause

Fields

• renderGroupByClause :: ByteString

Instances

Eq (GroupByClause grp from)

Defined in Squeal.PostgreSQL.Query.Table

Methods

(==) :: GroupByClause grp from -> GroupByClause grp from -> Bool

(/=) :: GroupByClause grp from -> GroupByClause grp from -> Bool

Ord (GroupByClause grp from)

Defined in Squeal.PostgreSQL.Query.Table

Methods

compare :: GroupByClause grp from -> GroupByClause grp from -> Ordering

(<) :: GroupByClause grp from -> GroupByClause grp from -> Bool

(<=) :: GroupByClause grp from -> GroupByClause grp from -> Bool

(>) :: GroupByClause grp from -> GroupByClause grp from -> Bool

(>=) :: GroupByClause grp from -> GroupByClause grp from -> Bool

max :: GroupByClause grp from -> GroupByClause grp from -> GroupByClause grp from

min :: GroupByClause grp from -> GroupByClause grp from -> GroupByClause grp from

Show (GroupByClause grp from)

Defined in Squeal.PostgreSQL.Query.Table

Methods

showsPrec :: Int -> GroupByClause grp from -> ShowS

show :: GroupByClause grp from -> String

showList :: [GroupByClause grp from] -> ShowS

Generic (GroupByClause grp from)

Defined in Squeal.PostgreSQL.Query.Table

Associated Types

type Rep (GroupByClause grp from) :: Type -> Type

Methods

from :: GroupByClause grp from -> Rep (GroupByClause grp from) x

to :: Rep (GroupByClause grp from) x -> GroupByClause grp from

NFData (GroupByClause grp from)

Defined in Squeal.PostgreSQL.Query.Table

Methods

rnf :: GroupByClause grp from -> ()

RenderSQL (GroupByClause grp from)

Defined in Squeal.PostgreSQL.Query.Table

Methods

renderSQL :: GroupByClause grp from -> ByteString

type Rep (GroupByClause grp from)

Defined in Squeal.PostgreSQL.Query.Table

type Rep (GroupByClause grp from) = D1 (MetaData "GroupByClause" "Squeal.PostgreSQL.Query.Table" "squeal-postgresql-0.6.0.0-56EGnKmL3FAInHQPvmCKa1" True) (C1 (MetaCons "UnsafeGroupByClause" PrefixI True) (S1 (MetaSel (Just "renderGroupByClause") NoSourceUnpackedness NoSourceStrictness DecidedLazy) (Rec0 ByteString)))

data HavingClause grp lat with db params from where

A HavingClause is used to eliminate groups that are not of interest. An Ungrouped TableExpression may only use NoHaving while a Grouped TableExpression must use Having whose conditions are combined with .&&.

Constructors

NoHaving :: HavingClause Ungrouped lat with db params from

Having :: [Condition (Grouped bys) lat with db params from] -> HavingClause (Grouped bys) lat with db params from

Instances

Eq (HavingClause grp lat with db params from)

Defined in Squeal.PostgreSQL.Query.Table

Methods

(==) :: HavingClause grp lat with db params from -> HavingClause grp lat with db params from -> Bool

(/=) :: HavingClause grp lat with db params from -> HavingClause grp lat with db params from -> Bool

Ord (HavingClause grp lat with db params from)

Defined in Squeal.PostgreSQL.Query.Table

Methods

compare :: HavingClause grp lat with db params from -> HavingClause grp lat with db params from -> Ordering

(<) :: HavingClause grp lat with db params from -> HavingClause grp lat with db params from -> Bool

(<=) :: HavingClause grp lat with db params from -> HavingClause grp lat with db params from -> Bool

(>) :: HavingClause grp lat with db params from -> HavingClause grp lat with db params from -> Bool

(>=) :: HavingClause grp lat with db params from -> HavingClause grp lat with db params from -> Bool

max :: HavingClause grp lat with db params from -> HavingClause grp lat with db params from -> HavingClause grp lat with db params from

min :: HavingClause grp lat with db params from -> HavingClause grp lat with db params from -> HavingClause grp lat with db params from

Show (HavingClause grp lat with db params from)

Defined in Squeal.PostgreSQL.Query.Table

Methods

showsPrec :: Int -> HavingClause grp lat with db params from -> ShowS

show :: HavingClause grp lat with db params from -> String

showList :: [HavingClause grp lat with db params from] -> ShowS

RenderSQL (HavingClause grp lat with db params from)

Render a HavingClause.

Defined in Squeal.PostgreSQL.Query.Table

Methods

renderSQL :: HavingClause grp lat with db params from -> ByteString