221 lines
8.4 KiB
Plaintext
221 lines
8.4 KiB
Plaintext
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> -- | The AST for SQL queries
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> module Language.SQL.SimpleSQL.Syntax
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> (-- * Scalar expressions
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> ScalarExpr(..)
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> ,TypeName(..)
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> ,Duplicates(..)
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> ,Direction(..)
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> ,InThing(..)
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> ,SubQueryExprType(..)
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> -- * Query expressions
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> ,QueryExpr(..)
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> ,makeSelect
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> ,CombineOp(..)
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> ,Corresponding(..)
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> -- ** From
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> ,TableRef(..)
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> ,JoinType(..)
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> ,JoinCondition(..)
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> ) where
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> -- | Represents a scalar expression
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> data ScalarExpr = -- | a numeric literal optional decimal point, e+-
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> -- integral exponent, e.g
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> --
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> -- * 10
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> --
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> -- * 10.
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> --
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> -- * .1
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> --
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> -- * 10.1
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> --
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> -- * 1e5
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> --
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> -- * 12.34e-6
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> NumLit String
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> -- | string literal, currently only basic strings
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> -- between single quotes without escapes (no
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> -- single quotes in strings then)
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> | StringLit String
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> -- | text of interval literal, units of interval
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> -- precision, e.g. interval 3 days (3)
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> | IntervalLit String
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> String
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> (Maybe Int)
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> -- | identifier without dots
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> | Iden String
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> -- | identifier with one dot
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> | Iden2 String String
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> -- | star
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> | Star
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> -- | star with qualifier, e.g t.*
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> | Star2 String
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> -- | function application (anything that looks
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> -- like c style function application syntactically)
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> | App String [ScalarExpr]
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> -- | aggregate application, which adds distinct or
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> -- all, and order by, to regular function
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> -- application
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> | AggregateApp String (Maybe Duplicates)
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> [ScalarExpr]
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> [(ScalarExpr,Direction)]
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> -- | window application, which adds over
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> -- (partition by a order by b) to regular function
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> -- application. Explicit frames are not currently
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> -- supported
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> | WindowApp String [ScalarExpr] [ScalarExpr] [(ScalarExpr,Direction)]
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> -- | Infix binary operators. This is used for
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> -- symbol operators (a + b), keyword operators (a
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> -- and b) and multiple keyword operators (a is
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> -- similar to b)
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> | BinOp ScalarExpr String ScalarExpr
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> -- | Prefix unary operators. This is used for
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> -- symbol operators, keyword operators and
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> -- multiple keyword operators
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> | PrefixOp String ScalarExpr
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> -- | Postfix unary operators. This is used for
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> -- symbol operators, keyword operators and multiple
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> -- keyword operators
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> | PostfixOp String ScalarExpr
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> -- | Used for ternary, mixfix and other non
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> -- orthodox operators, including the function
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> -- looking calls which use keywords instead of
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> -- commas to separate the arguments,
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> -- e.g. substring(t from 1 to 5)
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> | SpecialOp String [ScalarExpr]
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> -- | case expression. both flavours
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> -- supported. Multiple condition when branches not
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> -- currently supported (case when a=4,b=5 then x
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> -- end)
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> | Case (Maybe ScalarExpr) -- test value
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> [(ScalarExpr,ScalarExpr)] -- when branches
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> (Maybe ScalarExpr) -- else value
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> | Parens ScalarExpr
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> -- | cast(a as typename)
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> | Cast ScalarExpr TypeName
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> -- | prefix 'typed literal', e.g. int '42'
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> | CastOp TypeName String
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> -- | exists, all, any, some subqueries
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> | SubQueryExpr SubQueryExprType QueryExpr
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> -- | in list literal and in subquery, if the bool
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> -- is false it means not in was used ('a not in
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> -- (1,2)')
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> | In Bool -- true if in, false if not in
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> ScalarExpr InThing
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> deriving (Eq,Show,Read)
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> -- | Represents a type name, used in casts.
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> data TypeName = TypeName String deriving (Eq,Show,Read)
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> -- | Used for 'expr in (scalar expression list)', and 'expr in
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> -- | (subquery)' syntax
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> data InThing = InList [ScalarExpr]
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> | InQueryExpr QueryExpr
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> deriving (Eq,Show,Read)
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> -- | A subquery in a scalar expression
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> data SubQueryExprType
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> = -- | exists (query expr)
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> SqExists
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> -- | a scalar subquery
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> | SqSq
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> -- | all (query expr)
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> | SqAll
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> -- | some (query expr)
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> | SqSome
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> -- | any (query expr)
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> | SqAny
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> deriving (Eq,Show,Read)
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> -- | Represents a query expression, which can be:
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> --
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> -- * a regular select;
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> --
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> -- * a set operator (union, except, intersect);
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> --
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> -- * a common table expression (with);
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> --
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> -- * a values expression (not yet supported);
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> --
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> -- * or the table syntax - 'table t', shorthand for 'select * from
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> -- t' (not yet supported).
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> data QueryExpr
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> = Select
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> {qeDuplicates :: Duplicates
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> ,qeSelectList :: [(Maybe String,ScalarExpr)] -- ^ the column aliases and the expressions
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> ,qeFrom :: [TableRef]
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> ,qeWhere :: Maybe ScalarExpr
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> ,qeGroupBy :: [ScalarExpr]
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> ,qeHaving :: Maybe ScalarExpr
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> ,qeOrderBy :: [(ScalarExpr,Direction)]
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> ,qeLimit :: Maybe ScalarExpr
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> ,qeOffset :: Maybe ScalarExpr
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> }
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> | CombineQueryExpr
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> {qe1 :: QueryExpr
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> ,qeCombOp :: CombineOp
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> ,qeDuplicates :: Duplicates
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> ,qeCorresponding :: Corresponding
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> ,qe2 :: QueryExpr
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> }
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> | With [(String,QueryExpr)] QueryExpr
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> deriving (Eq,Show,Read)
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TODO: add queryexpr parens to deal with e.g.
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(select 1 union select 2) union select 3
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I'm not sure if this is valid syntax or not
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> -- | represents the Distinct or All keywords, which can be used
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> -- before a select list, in an aggregate/window function
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> -- application, or in a query expression set operator
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> data Duplicates = Distinct | All deriving (Eq,Show,Read)
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> -- | The direction for a column in order by.
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> data Direction = Asc | Desc deriving (Eq,Show,Read)
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> -- | Query expression set operators
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> data CombineOp = Union | Except | Intersect deriving (Eq,Show,Read)
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> -- | Corresponding, an option for the set operators
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> data Corresponding = Corresponding | Respectively deriving (Eq,Show,Read)
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> -- | helper/'default' value for query exprs to make creating query expr values a little easier
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> makeSelect :: QueryExpr
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> makeSelect = Select {qeDuplicates = All
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> ,qeSelectList = []
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> ,qeFrom = []
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> ,qeWhere = Nothing
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> ,qeGroupBy = []
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> ,qeHaving = Nothing
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> ,qeOrderBy = []
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> ,qeLimit = Nothing
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> ,qeOffset = Nothing}
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> -- | Represents a entry in the csv of tables in the from clause.
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> data TableRef = -- | from t
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> TRSimple String
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> -- | from a join b
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> | TRJoin TableRef JoinType TableRef (Maybe JoinCondition)
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> -- | from (a)
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> | TRParens TableRef
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> -- | from a as b(c,d)
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> | TRAlias TableRef String (Maybe [String])
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> -- | from (query expr)
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> | TRQueryExpr QueryExpr
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> deriving (Eq,Show,Read)
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TODO: add function table ref
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> -- | The type of a join
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> data JoinType = JInner | JLeft | JRight | JFull | JCross
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> deriving (Eq,Show,Read)
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> -- | The join condition.
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> data JoinCondition = JoinOn ScalarExpr -- ^ on expr
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> | JoinUsing [String] -- ^ using (column list)
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> | JoinNatural -- ^ natural join was used
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> deriving (Eq,Show,Read)
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