Database.HaskellDB.PrimQuery

PrimQuery defines the datatype of relational expressions (PrimQuery) and some useful functions on PrimQuery's

Type Declarations

Types

type TableName = String

type Attribute = String

type Scheme = [Attribute]

type Assoc = [(Attribute, PrimExpr)]

type Name = String

Data types

data PrimQuery

Constructors

BaseTable TableName Scheme

Project Assoc PrimQuery

Restrict PrimExpr PrimQuery

Group Assoc PrimQuery

Binary RelOp PrimQuery PrimQuery

Special SpecialOp PrimQuery

Empty

Instances

Show PrimQuery

data RelOp

Constructors

Times

Union

Intersect

Divide

Difference

Instances

Show RelOp

data SpecialOp

Constructors

Order [OrderExpr]

Top Int

Instances

Show SpecialOp

data PrimExpr

Constructors

AttrExpr Attribute

BinExpr BinOp PrimExpr PrimExpr

UnExpr UnOp PrimExpr

AggrExpr AggrOp PrimExpr

ConstExpr Literal

CaseExpr [(PrimExpr, PrimExpr)] PrimExpr

ListExpr [PrimExpr]

ParamExpr (Maybe Name) PrimExpr

FunExpr Name [PrimExpr]

CastExpr Name PrimExpr

Cast an expression to a given type.

Instances

Read PrimExpr

Show PrimExpr

data OrderExpr

Constructors

OrderExpr OrderOp PrimExpr

Instances

Show OrderExpr

data BinOp

Constructors

OpEq

OpLt

OpLtEq

OpGt

OpGtEq

OpNotEq

OpAnd

OpOr

OpLike

OpIn

OpOther String

OpCat

OpPlus

OpMinus

OpMul

OpDiv

OpMod

OpBitNot

OpBitAnd

OpBitOr

OpBitXor

OpAsg

Instances

Read BinOp

Show BinOp

data UnOp

Constructors

OpNot

OpIsNull

OpIsNotNull

OpLength

UnOpOther String

Instances

Read UnOp

Show UnOp

data OrderOp

Constructors

OpAsc

OpDesc

Instances

Show OrderOp

data AggrOp

Constructors

AggrCount

AggrSum

AggrAvg

AggrMin

AggrMax

AggrStdDev

AggrStdDevP

AggrVar

AggrVarP

AggrOther String

Instances

Read AggrOp

Show AggrOp

data Literal

Constructors

NullLit

DefaultLit

represents a default value

BoolLit Bool

StringLit String

IntegerLit Integer

DoubleLit Double

DateLit CalendarTime

OtherLit String

used for hacking in custom SQL

Instances

Read Literal

Show Literal

Function declarations

extend :: Assoc -> PrimQuery -> PrimQuery

Creates a projection of some attributes while keeping all other attributes in the relation visible too.

times :: PrimQuery -> PrimQuery -> PrimQuery

Takes the cartesian product of two queries.

attributes :: PrimQuery -> Scheme

Returns the schema (the attributes) of a query

attrInExpr :: PrimExpr -> Scheme

Returns all attributes in an expression.

attrInOrder :: [OrderExpr] -> Scheme

Returns all attributes in a list of ordering expressions.

substAttr :: Assoc -> PrimExpr -> PrimExpr

Substitute attribute names in an expression.

isAggregate :: PrimExpr -> Bool

isConstant :: PrimExpr -> Bool

Determines if a primitive expression represents a constant or is an expression only involving constants.

foldPrimQuery :: (t, TableName -> Scheme -> t, Assoc -> t -> t, PrimExpr -> t -> t, RelOp -> t -> t -> t, Assoc -> t -> t, SpecialOp -> t -> t) -> PrimQuery -> t

Fold on PrimQuery

foldPrimExpr :: (Attribute -> t, Literal -> t, BinOp -> t -> t -> t, UnOp -> t -> t, AggrOp -> t -> t, [(t, t)] -> t -> t, [t] -> t, Maybe Name -> t -> t, Name -> [t] -> t, Name -> t -> t) -> PrimExpr -> t

Fold on PrimExpr