4630006e9f
git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@1481 b08c6af1-5177-4d33-ba66-4b1c6b8b522a
1415 lines
44 KiB
Prolog
1415 lines
44 KiB
Prolog
% -*- Mode: Prolog -*-
|
|
% --------------------------------------------------------------------------------------
|
|
%
|
|
% This Prolog to SQL compiler may be distributed free of charge provided that it is
|
|
% not used in commercial applications without written consent of the author, and
|
|
% that the copyright notice remains unchanged.
|
|
%
|
|
% (C) Copyright by Christoph Draxler, Munich
|
|
% Version 1.1 of Dec. 21st 1992
|
|
%
|
|
% I would like to keep in my hands the further development and distribution of the
|
|
% compiler. This does not mean that I don't want other people to suggest or even
|
|
% implement improvements - quite on the contrary: I greatly appreciate contributions
|
|
% and if they make sense to me I will incorporate them into the compiler (with due
|
|
% credits given!).
|
|
%
|
|
% For further development of the compiler, address your requests, comments and
|
|
% criticism to the author:
|
|
%
|
|
% Christoph Draxler
|
|
% CIS Centre for Information and Speech Processing
|
|
% Ludwig-Maximilians-University Munich
|
|
% Wagmuellerstr. 23
|
|
% D 80538 Munich
|
|
% Tel : ++49 / +89 / 211 06 64 (-60)
|
|
% Fax : ++49 / +89 / 211 06 74
|
|
% Mail: draxler@cis.uni-muenchen.de
|
|
%
|
|
%
|
|
% A report describing the implementation is available upon request from the
|
|
% author.
|
|
%
|
|
%
|
|
% RELEASE INFORMATION
|
|
% ===================
|
|
% Current version is v. 1.1 of Dec. 21st 1992.
|
|
% Version 1.0 Sept. 3 1992
|
|
% --------------------------------------------------------------------------------------
|
|
|
|
|
|
:- module(myddas_prolog2sql,[
|
|
translate/3,
|
|
queries_atom/2
|
|
]).
|
|
|
|
|
|
|
|
|
|
|
|
|
|
% --------------------------------------------------------------------------------------
|
|
%
|
|
% Top level predicate translate/3 organizes the compilation and constructs a
|
|
% Prolog term representation of the SQL query.
|
|
%
|
|
% --------------------------------------------------------------------------------------
|
|
|
|
|
|
translate(ProjectionTerm,DatabaseGoal,SQLQueryTerm):-
|
|
% --- initialize variable identifiers and range variables for relations -----
|
|
init_gensym(var),
|
|
init_gensym(rel),
|
|
|
|
% --- tokenize projection term and database goal ----------------------------
|
|
tokenize_term(DatabaseGoal,TokenDatabaseGoal),
|
|
tokenize_term(ProjectionTerm,TokenProjectionTerm),
|
|
|
|
% --- lexical analysis: reordering of goals for disjunctive normalized form -
|
|
disjunction(TokenDatabaseGoal,Disjunction),
|
|
|
|
% --- code generation ---------------------------------------------------------------
|
|
query_generation(Disjunction,TokenProjectionTerm,SQLQueryTerm).
|
|
|
|
|
|
|
|
|
|
|
|
% --- disjunction(Goal,Disjunction) ----------------------------------------------------
|
|
%
|
|
% turns original goal into disjunctive normalized form by computing all conjunctions
|
|
% and collecting them in a list
|
|
%
|
|
% --------------------------------------------------------------------------------------
|
|
|
|
disjunction(Goal,Disjunction):-
|
|
findall(Conjunction,linearize(Goal,Conjunction),Disjunction).
|
|
|
|
|
|
|
|
|
|
% --- linearize(Goal,ConjunctionList) --------------------------------------------------
|
|
%
|
|
% Returns a conjunction of base goals for a complex disjunctive or conjunctive goal
|
|
% Yields several solutions upon backtracking for disjunctive goals
|
|
%
|
|
% --------------------------------------------------------------------------------------
|
|
|
|
linearize(((A,B),C),(LinA,(LinB,LinC))):-
|
|
% --- transform left-linear to right-linear conjunction (',' is associative) ----
|
|
linearize(A,LinA),
|
|
linearize(B,LinB),
|
|
linearize(C,LinC).
|
|
|
|
linearize((A,B),(LinA,LinB)):-
|
|
A \= (_,_),
|
|
% --- make sure A is not a conjunction ------------------------------------------
|
|
linearize(A,LinA),
|
|
linearize(B,LinB).
|
|
|
|
% ILP
|
|
%linearize((A;B),LinA):-
|
|
linearize((A;_),LinA):-
|
|
linearize(A,LinA).
|
|
|
|
% ILP
|
|
%linearize((A;B),LinB):-
|
|
linearize((_;B),LinB):-
|
|
linearize(B,LinB).
|
|
|
|
linearize(not A, not LinA):-
|
|
linearize(A,LinA).
|
|
|
|
linearize(Var^A, Var^LinA):-
|
|
linearize(A,LinA).
|
|
|
|
linearize(A,A):-
|
|
A \= (_,_),
|
|
A \= (_;_),
|
|
A \= _^_,
|
|
A \= not(_).
|
|
|
|
|
|
|
|
|
|
% --- tokenize_term(Term,TokenizedTerm) -------------------------------------------------
|
|
%
|
|
% If Term is a
|
|
%
|
|
% - variable, then this variable is instantiated with a unique identifier
|
|
% of the form '$var$'(VarId), and TokenizedTerm is bound to the same
|
|
% term '$var$'(VarId).
|
|
%
|
|
% - constant, then TokenizedTerm is bound to '$const$'(Term).
|
|
%
|
|
% - complex term, then the term is decomposed, its arguments are tokenized,
|
|
% and TokenizedTerm is bound to the result of the composition of the original
|
|
% functor and the tokenized arguments.
|
|
%
|
|
% --------------------------------------------------------------------------------------
|
|
|
|
tokenize_term('$var$'(VarId),'$var$'(VarId)):-
|
|
var(VarId),
|
|
% --- uninstantiated variable: instantiate it with unique identifier.
|
|
gensym(var,VarId).
|
|
|
|
tokenize_term('$var$'(VarId),'$var$'(VarId)):-
|
|
nonvar(VarId).
|
|
|
|
tokenize_term(Constant,'$const$'(Constant)):-
|
|
nonvar(Constant),
|
|
functor(Constant,_,0).
|
|
|
|
tokenize_term(Term,TokenizedTerm):-
|
|
nonvar(Term),
|
|
Term \= '$var$'(_),
|
|
Term \= '$const$'(_),
|
|
Term =.. [Functor|Arguments],
|
|
Arguments \= [],
|
|
tokenize_arguments(Arguments,TokenArguments),
|
|
TokenizedTerm =.. [Functor|TokenArguments].
|
|
|
|
|
|
|
|
% --- tokenize_arguments(Arguments,TokenizedArguments) ---------------------------------
|
|
%
|
|
% organizes tokenization of arguments by traversing list and calling tokenize_term
|
|
% for each element of the list.
|
|
%
|
|
% --------------------------------------------------------------------------------------
|
|
|
|
tokenize_arguments([],[]).
|
|
|
|
tokenize_arguments([FirstArg|RestArgs],[TokFirstArg|TokRestArgs]):-
|
|
tokenize_term(FirstArg,TokFirstArg),
|
|
tokenize_arguments(RestArgs,TokRestArgs).
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
% --- query_generation(ListOfConjunctions, ProjectionTerm, ListOfQueries) --------------
|
|
%
|
|
% For each Conjunction translate the pair (ProjectionTerm,Conjunction) to an SQL query
|
|
% and connect each such query through a UNION-operator to result in the ListOfQueries.
|
|
%
|
|
% A Conjunction consists of positive or negative subgoals. Each subgoal is translated
|
|
% as follows:
|
|
% - the functor of a goal that is not a comparison operation is translated to
|
|
% a relation name with a range variable
|
|
% - negated goals are translated to NOT EXISTS-subqueries with * projection
|
|
% - comparison operations are translated to comparison operations in the WHERE-clause
|
|
% - aggregate function terms are translated to aggregate function (sub)queries
|
|
%
|
|
% The arguments of a goal are translated as follows:
|
|
% - variables of a goal are translated to qualified attributes
|
|
% - variables occurring in several goals are translated to equality comparisons
|
|
% (equi join) in the WHERE-clause
|
|
% - constant arguments are translated to equality comparisons in the WHERE-clause
|
|
%
|
|
% Special treatment of arithmetic functions:
|
|
% - arithmetic functions are identified through the Prolog is/2 operator
|
|
% - an arithmetic function may contain an unbound variable only on its left side
|
|
% - the right side of the is/2 operator may consist of
|
|
% * bound variables (bound through occurrence within a positive database goal, or
|
|
% bound through preceeding arithmetic function), or of
|
|
% * constants (numbers, i.e. integers, reals)
|
|
%
|
|
% The following RESTRICTION holds:
|
|
%
|
|
% - the binding of variables follows Prolog: variables are bound by positive base goals
|
|
% and on the left side of the is/2 predicate - comparison operations, negated goals
|
|
% and right sides of the is/2 predicate do not return variable bindings and may even
|
|
% require all arguments to be bound for a safe evaluation.
|
|
%
|
|
% --------------------------------------------------------------------------------------
|
|
|
|
query_generation([],_,[]).
|
|
|
|
query_generation([Conjunction|Conjunctions],ProjectionTerm,[Query|Queries]):-
|
|
projection_term_variables(ProjectionTerm,InitDict),
|
|
translate_conjunction(Conjunction,SQLFrom,SQLWhere,InitDict,Dict),
|
|
translate_projection(ProjectionTerm,Dict,SQLSelect),
|
|
Query = query(SQLSelect,SQLFrom,SQLWhere),
|
|
query_generation(Conjunctions,ProjectionTerm,Queries).
|
|
|
|
|
|
|
|
% --- translate_goal(Goal,SQLFrom,SQLWhere,Dict,NewDict) -------------------------------
|
|
%
|
|
% translates a
|
|
%
|
|
% - positive database goal to the associated FROM- and WHERE clause of an SQL query
|
|
% - a negated goal to a negated existential subquery
|
|
% - an arithmetic goal to an arithmetic expression or an aggregate function query
|
|
% - a comparison goal to a comparison expression
|
|
% - a negated comparison goal to a comparison expression with the opposite comparison
|
|
% operator
|
|
%
|
|
% --------------------------------------------------------------------------------------
|
|
|
|
translate_goal(SimpleGoal,[SQLFrom],SQLWhere,Dict,NewDict):-
|
|
% --- positive goal binds variables - these bindings are held in the dictionary -----
|
|
functor(SimpleGoal,Functor,Arity),
|
|
translate_functor(Functor,Arity,SQLFrom),
|
|
SimpleGoal =.. [Functor|Arguments],
|
|
translate_arguments(Arguments,SQLFrom,1,SQLWhere,Dict,NewDict).
|
|
|
|
translate_goal(Result is Expression,[],SQLWhere,Dict,NewDict):-
|
|
translate_arithmetic_function(Result,Expression,SQLWhere,Dict,NewDict).
|
|
|
|
translate_goal(not NegatedGoals,[],SQLNegatedSubquery,Dict,Dict):-
|
|
% --- negated goals do not bind variables - hence Dict is returned unchanged --------
|
|
functor(NegatedGoals,Functor,_),
|
|
not comparison(Functor,_),
|
|
translate_conjunction(NegatedGoals,SQLFrom,SQLWhere,Dict,_),
|
|
SQLNegatedSubquery = [negated_existential_subquery([*],SQLFrom,SQLWhere)].
|
|
|
|
translate_goal(not ComparisonGoal,[],SQLCompOp,Dict,Dict):-
|
|
% --- comparison operations do not bind variables - Dict is returned unchanged ------
|
|
ComparisonGoal =.. [ComparisonOperator,LeftArg,RightArg],
|
|
comparison(ComparisonOperator,SQLOperator),
|
|
negated_comparison(SQLOperator,SQLNegOperator),
|
|
translate_comparison(LeftArg,RightArg,SQLNegOperator,Dict,SQLCompOp).
|
|
|
|
translate_goal(ComparisonGoal,[],SQLCompOp,Dict,Dict):-
|
|
% --- comparison operations do not bind variables - Dict is returned unchanged ------
|
|
ComparisonGoal =.. [ComparisonOperator,LeftArg,RightArg],
|
|
comparison(ComparisonOperator,SQLOperator),
|
|
translate_comparison(LeftArg,RightArg,SQLOperator,Dict,SQLCompOp).
|
|
|
|
%DISTINCT
|
|
translate_goal(distinct(Goal),List,SQL,Dict,DistinctDict):-!,
|
|
translate_goal(Goal,List,SQL,Dict,NewDict),
|
|
add_distinct_statement(NewDict,DistinctDict).
|
|
|
|
%DEBUG
|
|
add_distinct_statement(Dict,Dict):-
|
|
append([_],[1,2],_).
|
|
|
|
|
|
|
|
% --- translate_conjunction(Conjunction,SQLFrom,SQLWhere,Dict,NewDict) -----------------
|
|
%
|
|
% translates a conjunction of goals (represented as a list of goals preceeded by
|
|
% existentially quantified variables) to FROM- and WHERE-clause of an SQL query.
|
|
% A dictionary containing the associated SQL table and attribute names is built up
|
|
% as an accumulator pair (arguments Dict and NewDict)
|
|
%
|
|
% --------------------------------------------------------------------------------------
|
|
|
|
translate_conjunction('$var$'(VarId)^Goal,SQLFrom,SQLWhere,Dict,NewDict):-
|
|
% --- add info on existentially quantified variables to dictionary here -------------
|
|
add_to_dictionary(VarId,_,_,_,existential,Dict,TmpDict),
|
|
translate_conjunction(Goal,SQLFrom,SQLWhere,TmpDict,NewDict).
|
|
|
|
translate_conjunction(Goal,SQLFrom,SQLWhere,Dict,NewDict):-
|
|
Goal \= (_,_),
|
|
translate_goal(Goal,SQLFrom,SQLWhere,Dict,NewDict).
|
|
|
|
translate_conjunction((Goal,Conjunction),SQLFrom,SQLWhere,Dict,NewDict):-
|
|
translate_goal(Goal,FromBegin,WhereBegin,Dict,TmpDict),
|
|
translate_conjunction(Conjunction,FromRest,WhereRest,TmpDict,NewDict),
|
|
append(FromBegin,FromRest,SQLFrom),
|
|
append(WhereBegin,WhereRest,SQLWhere).
|
|
|
|
|
|
|
|
|
|
|
|
% --- translate_arithmetic_function(Result,Expression,SQLWhere,Dict,NewDict) -----------
|
|
%
|
|
% Arithmetic functions (left side of is/2 operator is bound to value of expression on
|
|
% right side) may be called with either
|
|
%
|
|
% - Result unbound: then Result is bound to the value of the evaluation of Expression
|
|
% - Result bound: then an equality condition is returned between the value of Result
|
|
% and the value of the evaluation of Expression.
|
|
%
|
|
% Only the equality test shows up in the WHERE clause of an SQLquery.
|
|
%
|
|
% --------------------------------------------------------------------------------------
|
|
|
|
translate_arithmetic_function('$var$'(VarId),Expression,[],Dict,NewDict):-
|
|
% assigment of value of arithmetic expression to variable - does not
|
|
% show up in WHERE-part, but expression corresponding to
|
|
% variable must be stored in Dict for projection translation
|
|
|
|
evaluable_expression(Expression,Dict,ArithExpression,Type),
|
|
add_to_dictionary(VarId,is,ArithExpression,Type,all,Dict,NewDict).
|
|
|
|
|
|
translate_arithmetic_function('$var$'(VarId),Expression,ArithComparison,Dict,Dict):-
|
|
% --- test whether left side evaluates to right side: return equality comparison ----
|
|
% Left side consists of qualified attribute, i.e. range variable must not be
|
|
% arithmetic operator is/2
|
|
|
|
lookup(VarId,Dict,PrevRangeVar,PrevAtt,PrevType),
|
|
not (PrevRangeVar = is),
|
|
|
|
% test whether type of attribute is numeric - if not, there's no sense in
|
|
% continuing the translation
|
|
|
|
type_compatible(PrevType,number),
|
|
evaluable_expression(Expression,Dict,ArithExpression,ExprType),
|
|
type_compatible(ExprType,number),
|
|
ArithComparison = [comp(att(PrevRangeVar,PrevAtt),'=',ArithExpression)].
|
|
|
|
|
|
translate_arithmetic_function('$var$'(VarId),Expression,ArithComparison,Dict,Dict):-
|
|
% --- test whether left side evaluates to right side: return equality comparison ----
|
|
% Left side consists of arithmetic expression, i.e. VarId is stored in Dict as
|
|
% belonging to arithmetic expression which is expressed as RangeVar-argument
|
|
% of lookup returning is/2. Type information is implicit through the is/2 functor
|
|
|
|
lookup(VarId,Dict,is,LeftExpr,Type),
|
|
type_compatible(Type,number),
|
|
evaluable_expression(Expression,Dict,RightExpr,ExprType),
|
|
type_compatible(ExprType,number),
|
|
ArithComparison = [comp(LeftExpr,'=',RightExpr)].
|
|
|
|
|
|
translate_arithmetic_function('$const$'(Constant),Expression,ArithComparison,Dict,Dict):-
|
|
% --- is/2 used to test whether left side evaluates to right side -------------------
|
|
get_type('$const$'(Constant),ConstantType),
|
|
type_compatible(ConstantType,number),
|
|
evaluable_expression(Expression,Dict,ArithExpression,ExprType),
|
|
type_compatible(ExprType,number),
|
|
ArithComparison = [comp('$const$'(Constant),'=',ArithExpression)].
|
|
|
|
|
|
|
|
% --- translate_comparison(LeftArg,RightArg,CompOp,Dict,SQLComparison) ---------
|
|
%
|
|
% translates the left and right arguments of a comparison term into the
|
|
% appropriate comparison operation in SQL. The result type of each
|
|
% argument expression is checked for type compatibility
|
|
%
|
|
% ------------------------------------------------------------------------------
|
|
|
|
translate_comparison(LeftArg,RightArg,CompOp,Dict,Comparison):-
|
|
evaluable_expression(LeftArg,Dict,LeftTerm,LeftArgType),
|
|
evaluable_expression(RightArg,Dict,RightTerm,RightArgType),
|
|
type_compatible(LeftArgType,RightArgType),
|
|
Comparison = [comp(LeftTerm,CompOp,RightTerm)].
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
% --- translate_functor(Functor,QualifiedTableName) ------------------------------------
|
|
%
|
|
% translate_functor searches for the matching relation table name for
|
|
% a given functor and creates a unique range variable to result in
|
|
% a unique qualified relation table name.
|
|
%
|
|
% --------------------------------------------------------------------------------------
|
|
|
|
translate_functor(Functor,Arity,rel(TableName,RangeVariable)):-
|
|
relation(Functor,Arity,TableName),
|
|
gensym(rel,RangeVariable).
|
|
|
|
|
|
|
|
|
|
% --- translate_arguments(Arguments,RelTable,ArgPos,Conditions,Dict) -------------------
|
|
%
|
|
% translate_arguments organizes the translation of term arguments. One
|
|
% term argument after the other is taken from the list of term arguments
|
|
% until the list is exhausted.
|
|
%
|
|
% --------------------------------------------------------------------------------------
|
|
|
|
translate_arguments([],_,_,[],Dict,Dict).
|
|
|
|
translate_arguments([Arg|Args],SQLTable,Position,SQLWhere,Dict,NewDict):-
|
|
translate_argument(Arg,SQLTable,Position,Where,Dict,TmpDict),
|
|
NewPosition is Position + 1,
|
|
translate_arguments(Args,SQLTable,NewPosition,RestWhere,TmpDict,NewDict),
|
|
append(Where,RestWhere,SQLWhere).
|
|
|
|
|
|
|
|
|
|
% --- translate_argument(Argument,RelTable,Position,Condition,Dict) --------------------
|
|
%
|
|
% The first occurrence of a variable leads to its associated SQL attribute information
|
|
% to be recorded in the Dict. Any further occurrence creates an equi-join condition
|
|
% between the current attribute and the previously recorded attribute.
|
|
% Constant arguments always translate to equality comparisons between an attribute and
|
|
% the constant value.
|
|
%
|
|
% --------------------------------------------------------------------------------------
|
|
|
|
translate_argument('$var$'(VarId),rel(SQLTable,RangeVar),Position,[],Dict,NewDict):-
|
|
attribute(Position,SQLTable,Attribute,Type),
|
|
add_to_dictionary(VarId,RangeVar,Attribute,Type,all,Dict,NewDict).
|
|
|
|
translate_argument('$var$'(VarId),rel(SQLTable,RangeVar),Position,AttComparison,Dict,Dict):-
|
|
% --- Variable occurred previously - retrieve first occurrence data from dictionary -
|
|
lookup(VarId,Dict,PrevRangeVar,PrevAtt,PrevType),
|
|
attribute(Position,SQLTable,Attribute,Type),
|
|
type_compatible(PrevType,Type),
|
|
AttComparison = [comp(att(RangeVar,Attribute),=,att(PrevRangeVar,PrevAtt))].
|
|
|
|
translate_argument('$const$'(Constant),rel(SQLTable,RangeVar),Position,ConstComparison,Dict,Dict):-
|
|
% --- Equality comparison of constant value and attribute in table ------------------
|
|
attribute(Position,SQLTable,Attribute,Type),
|
|
get_type('$const$'(Constant),ConstType),
|
|
type_compatible(ConstType,Type),
|
|
ConstComparison = [comp(att(RangeVar,Attribute),=,'$const$'(Constant))].
|
|
|
|
|
|
|
|
|
|
|
|
% --- projection_term_variables(ProjectionTerm,Dict) -----------------------------------
|
|
%
|
|
% extracts all variables from the ProjectionTerm and places them into the
|
|
% Dict as a dict/4 term with their Identifier, a non instantiated RangeVar and
|
|
% Attribute argument, and the keyword existential for the type of quantification
|
|
%
|
|
% --------------------------------------------------------------------------------------
|
|
|
|
%% ERRO??
|
|
%projection_term_variables('$const(_)$',[]).
|
|
projection_term_variables('$const$'(_),[]).
|
|
|
|
projection_term_variables('$var$'(VarId),[dict(VarId,_,_,_,existential)]).
|
|
|
|
projection_term_variables(ProjectionTerm,ProjectionTermVariables):-
|
|
ProjectionTerm =.. [Functor|ProjectionTermList],
|
|
not (Functor = '$var$'),
|
|
not (ProjectionTermList = []),
|
|
projection_list_vars(ProjectionTermList,ProjectionTermVariables).
|
|
|
|
|
|
projection_list_vars([],[]).
|
|
projection_list_vars(['$var$'(VarId)|RestArgs],[dict(VarId,_,_,_,existential)|RestVars]):-
|
|
projection_list_vars(RestArgs,RestVars).
|
|
projection_list_vars(['$const$'(_)|RestArgs],Vars):-
|
|
projection_list_vars(RestArgs,Vars).
|
|
|
|
|
|
|
|
|
|
|
|
|
|
% --------------------------------------------------------------------------------------
|
|
% RESTRICTION! ProjectionTerm underlies the following restrictions:
|
|
%
|
|
% - ProjectionTerm must have a functor other than the built-in
|
|
% operators, i.e. ',',';', etc. are not allowed
|
|
%
|
|
% - only variables and constants are allowed as arguments,
|
|
% i.e. no structured terms
|
|
%
|
|
% --------------------------------------------------------------------------------------
|
|
|
|
translate_projection('$var$'(VarId),Dict,SelectList):-
|
|
projection_arguments(['$var$'(VarId)],SelectList,Dict).
|
|
|
|
translate_projection('$const$'(Const),_,['$const$'(Const)]).
|
|
|
|
translate_projection(ProjectionTerm,Dict,SelectList):-
|
|
ProjectionTerm =.. [Functor|Arguments],
|
|
not (Functor = '$var$'),
|
|
not (Functor = '$const$'),
|
|
not (Arguments = []),
|
|
projection_arguments(Arguments,SelectList,Dict).
|
|
|
|
|
|
|
|
projection_arguments([],[],_).
|
|
|
|
projection_arguments([Arg|RestArgs],[Att|RestAtts],Dict):-
|
|
retrieve_argument(Arg,Att,Dict),
|
|
projection_arguments(RestArgs,RestAtts,Dict).
|
|
|
|
|
|
|
|
|
|
% - retrieve_argument(Argument,SQLAttribute,Dictionary) --------------------------------
|
|
%
|
|
% retrieves the mapping of an argument to the appropriate SQL construct, i.e.
|
|
%
|
|
% - qualified attribute names for variables in base goals
|
|
% - arithmetic expressions for variables in arithmetic goals
|
|
% - constant values for constants
|
|
%
|
|
% --------------------------------------------------------------------------------------
|
|
|
|
retrieve_argument('$var$'(VarId),Attribute,Dict):-
|
|
lookup(VarId,Dict,TableName,AttName,_),
|
|
(
|
|
TableName = is ->
|
|
Attribute = AttName
|
|
;
|
|
Attribute = att(TableName,AttName)
|
|
).
|
|
|
|
retrieve_argument('$const$'(Constant),'$const$'(Constant),_).
|
|
|
|
|
|
|
|
|
|
|
|
% --- lookup(Key,Dict,Value) -----------------------------------------------------------
|
|
|
|
lookup(VarId,Dict,RangeVar,Attribute,Type):-
|
|
member(dict(VarId,RangeVar,Attribute,Type,Quant),Dict),
|
|
(
|
|
Quant = all ->
|
|
true
|
|
;
|
|
nonvar(RangeVar),
|
|
nonvar(Attribute)
|
|
).
|
|
|
|
|
|
|
|
% --- add_to_dictionary(Key,RangeVar,Attribute,Quantifier,Dict,NewDict) ----------------
|
|
|
|
add_to_dictionary(Key,RangeVar,Attribute,Type,_,Dict,Dict):-
|
|
member(dict(Key,RangeVar,Attribute,Type,existential),Dict).
|
|
|
|
add_to_dictionary(Key,RangeVar,Attribute,Type,Quantifier,Dict,NewDict):-
|
|
not member(dict(Key,_,_,_,_),Dict),
|
|
NewDict = [dict(Key,RangeVar,Attribute,Type,Quantifier)|Dict].
|
|
|
|
|
|
|
|
|
|
% --- aggregate_function(AggregateFunctionTerm,Dict,AggregateFunctionQuery) ------------
|
|
%
|
|
% aggregate_function discerns five Prolog aggregate function terms: count, avg, min,
|
|
% max, and sum. Each such term is has two arguments: a variable indicating the attribute
|
|
% over which the function is to be computed, and a goal argument which must contain in
|
|
% at least one argument position the variable:
|
|
%
|
|
% e.g. avg(Seats,plane(Type,Seats))
|
|
%
|
|
% These aggregate function terms correspond to the SQL built-in aggregate functions.
|
|
%
|
|
% RESTRICTION: AggregateGoal may only be conjunction of (positive or negative) base
|
|
% goals
|
|
%
|
|
% --------------------------------------------------------------------------------------
|
|
|
|
aggregate_function(AggregateFunctionTerm,Dict,AggregateFunctionExpression):-
|
|
AggregateFunctionTerm =..[AggFunctor,AggVar,AggGoal],
|
|
aggregate_functor(AggFunctor,SQLFunction),
|
|
conjunction(AggGoal,AggConjunction),
|
|
aggregate_query_generation(SQLFunction,AggVar,AggConjunction,Dict,AggregateFunctionExpression).
|
|
|
|
|
|
conjunction(Goal,Conjunction):-
|
|
disjunction(Goal,[Conjunction]).
|
|
|
|
|
|
|
|
|
|
% --- aggregate_query_generation(Function,FunctionVariable,AggGoal,Dict,AggregateQuery)
|
|
%
|
|
% compiles the function variable (representing the attribute over which the aggregate
|
|
% function is to be computed) and the aggregate goal (representing the selection and
|
|
% join conditions for the computation of the aggregate function) to an SQL aggregate
|
|
% function subquery.
|
|
%
|
|
% --------------------------------------------------------------------------------------
|
|
|
|
% ILP
|
|
% aggregate_query_generation(count,'$const$'('*'),AggGoal,Dict,AggregateQuery):-
|
|
% translate_conjunction(AggGoal,SQLFrom,SQLWhere,Dict,TmpDict),
|
|
% AggregateQuery = agg_query(Function,(count,['$const$'(*)]),SQLFrom,SQLWhere,[]).
|
|
|
|
aggregate_query_generation(count,'$const$'('*'),AggGoal,Dict,AggregateQuery):-
|
|
translate_conjunction(AggGoal,SQLFrom,SQLWhere,Dict,_),
|
|
|
|
% ATTENTION! It is assumed that in count(*) aggregate query terms there cannot be
|
|
% free variables because '*' stands for "all arguments"
|
|
|
|
AggregateQuery = agg_query(_,(count,['$const$'(*)]),SQLFrom,SQLWhere,[]).
|
|
|
|
%DISTINCT
|
|
aggregate_query_generation(countdistinct,'$const$'('*'),AggGoal,Dict,AggregateQuery):-
|
|
translate_conjunction(AggGoal,SQLFrom,SQLWhere,Dict,_),
|
|
|
|
% ATTENTION! It is assumed that in count(*) aggregate query terms there cannot be
|
|
% free variables because '*' stands for "all arguments"
|
|
|
|
AggregateQuery = agg_query(_,(countdistinct,['$const$'(*)]),SQLFrom,SQLWhere,[]).
|
|
|
|
|
|
aggregate_query_generation(Function,FunctionVariable,AggGoal,Dict,AggregateQuery):-
|
|
translate_conjunction(AggGoal,SQLFrom,SQLWhere,Dict,TmpDict),
|
|
|
|
% --- only variables occurring in the aggregate goal are relevant to the translation
|
|
% of the function variable and the free variables in the goal.
|
|
% Thus subtract from TmpDict all entries of Dict
|
|
set_difference(TmpDict,Dict,AggDict),
|
|
|
|
translate_projection(FunctionVariable,AggDict,SQLSelect),
|
|
translate_grouping(FunctionVariable,AggDict,SQLGroup),
|
|
AggregateQuery = agg_query(Function,SQLSelect,SQLFrom,SQLWhere,SQLGroup).
|
|
|
|
|
|
|
|
|
|
% --- translate_grouping(FunctionVariable,Dict,SQLGroup) -------------------------------
|
|
%
|
|
% finds the free variables in the aggregate function term and collects their
|
|
% corresponding SQL qualified attributes in the SQLGroup list.
|
|
%
|
|
% --------------------------------------------------------------------------------------
|
|
|
|
translate_grouping(FunctionVariable,Dict,SQLGroup):-
|
|
free_vars(FunctionVariable,Dict,FreeVariables),
|
|
translate_free_vars(FreeVariables,SQLGroup).
|
|
|
|
|
|
|
|
|
|
% --- free_vars(FunctionVariable,Dict,FreeVarList) -------------------------------------
|
|
%
|
|
% A Variable is free if it neither occurs as the FunctionVariable, nor is stored as
|
|
% existentially quantified (through ^/2 in the original goal) in the dictionary
|
|
%
|
|
% FreeVars contains for each variable the relevant attribute and relation information
|
|
% contained in the dictionary
|
|
%
|
|
% --------------------------------------------------------------------------------------
|
|
|
|
% ILP
|
|
% free_vars(FunctionVariable,Dict,FreeVarList):-
|
|
% projection_term_variables(FunctionVariable,FunctionVariableList),
|
|
% findall((Var,Table,Attribute),
|
|
% (member(dict(Var,Table,Attribute,Type,all),Dict),
|
|
% not member(dict(Var,_,_,_,_),FunctionVariableList)
|
|
% ),
|
|
% FreeVarList).
|
|
free_vars(FunctionVariable,Dict,FreeVarList):-
|
|
projection_term_variables(FunctionVariable,FunctionVariableList),
|
|
findall((Var,Table,Attribute),
|
|
(member(dict(Var,Table,Attribute,_,all),Dict),
|
|
not member(dict(Var,_,_,_,_),FunctionVariableList)
|
|
),
|
|
FreeVarList).
|
|
|
|
|
|
% --- function_variable_list(FunctionVariable,FunctionVariableList) --------------------
|
|
%
|
|
% extracts the list of variables which occur in the function variable term
|
|
%
|
|
% RESTRICTION: FunctionVariable may only contain one single variable.
|
|
%
|
|
% --------------------------------------------------------------------------------------
|
|
|
|
function_variable_list('$var$'(VarId),[VarId]).
|
|
|
|
|
|
|
|
|
|
% --- translate_free_vars(FreeVars,SQLGroup) -------------------------------------------
|
|
%
|
|
% translates dictionary information on free variables to SQLGroup of aggregate
|
|
% function query
|
|
%
|
|
% --------------------------------------------------------------------------------------
|
|
|
|
translate_free_vars([],[]).
|
|
% ILP
|
|
%translate_free_vars([(VarId,Table,Attribute)|FreeVars],[att(Table,Attribute)|SQLGroups]):-
|
|
translate_free_vars([(_,Table,Attribute)|FreeVars],[att(Table,Attribute)|SQLGroups]):-
|
|
translate_free_vars(FreeVars,SQLGroups).
|
|
|
|
|
|
|
|
|
|
% --- evaluable_expression(ExpressionTerm,Dictionary,Expression,Type) --------------------
|
|
%
|
|
% evaluable_expression constructs SQL arithmetic expressions with qualified attribute names
|
|
% from the Prolog arithmetic expression term and the information stored in the dictionary.
|
|
%
|
|
% The type of an evaluable function is returned in the argument Type.
|
|
%
|
|
% The dictionary is not changed because it is used for lookup only.
|
|
%
|
|
|
|
evaluable_expression(AggregateFunctionTerm,Dictionary,AggregateFunctionExpression,number):-
|
|
aggregate_function(AggregateFunctionTerm,Dictionary,AggregateFunctionExpression).
|
|
|
|
evaluable_expression(LeftExp + RightExp,Dictionary,LeftAr + RightAr,number):-
|
|
evaluable_expression(LeftExp,Dictionary,LeftAr,number),
|
|
evaluable_expression(RightExp,Dictionary,RightAr,number).
|
|
|
|
evaluable_expression(LeftExp - RightExp,Dictionary,LeftAr - RightAr,number):-
|
|
evaluable_expression(LeftExp,Dictionary,LeftAr,number),
|
|
evaluable_expression(RightExp,Dictionary,RightAr,number).
|
|
|
|
evaluable_expression(LeftExp * RightExp,Dictionary,LeftAr * RightAr,number):-
|
|
evaluable_expression(LeftExp,Dictionary,LeftAr,number),
|
|
evaluable_expression(RightExp,Dictionary,RightAr,number).
|
|
|
|
evaluable_expression(LeftExp / RightExp,Dictionary, LeftAr / RightAr,number):-
|
|
evaluable_expression(LeftExp,Dictionary,LeftAr,number),
|
|
evaluable_expression(RightExp,Dictionary,RightAr,number).
|
|
|
|
evaluable_expression('$var$'(VarId),Dictionary,att(RangeVar,Attribute),Type):-
|
|
lookup(VarId,Dictionary,RangeVar,Attribute,Type),
|
|
RangeVar \= is.
|
|
|
|
evaluable_expression('$var$'(VarId),Dictionary,ArithmeticExpression,Type):-
|
|
lookup(VarId,Dictionary,is,ArithmeticExpression,Type).
|
|
|
|
evaluable_expression('$const$'(Const),_,'$const$'(Const),ConstType):-
|
|
get_type('$const$'(Const),ConstType).
|
|
|
|
|
|
|
|
|
|
|
|
% --------------------------------------------------------------------------------------
|
|
%
|
|
% Output to screen predicates - rather crude at the moment
|
|
%
|
|
% --------------------------------------------------------------------------------------
|
|
|
|
|
|
% --- printqueries(Code) ---------------------------------------------------------------
|
|
|
|
printqueries([Query]):-
|
|
nl,
|
|
print_query(Query),
|
|
write(';'),
|
|
nl,
|
|
nl.
|
|
|
|
printqueries([Query|Queries]):-
|
|
not (Queries = []),
|
|
nl,
|
|
print_query(Query),
|
|
nl,
|
|
write('UNION'),
|
|
nl,
|
|
printqueries(Queries).
|
|
|
|
|
|
|
|
% --- print_query(QueryCode) -----------------------------------------------------------
|
|
|
|
print_query(query([agg_query(Function,Select,From,Where,Group)],_,_)):-
|
|
% --- ugly rule here: aggregate function only in SELECT Part of query ----
|
|
!,
|
|
print_query(agg_query(Function,Select,From,Where,Group)).
|
|
|
|
print_query(query(Select,From,Where)):-
|
|
print_clause('SELECT',Select,','),
|
|
nl,
|
|
print_clause('FROM',From,','),
|
|
nl,
|
|
print_clause('WHERE',Where,'AND'),
|
|
nl.
|
|
|
|
print_query(agg_query(Function,Select,From,Where,Group)):-
|
|
print_clause('SELECT',Function,Select,','),
|
|
nl,
|
|
print_clause('FROM',From,','),
|
|
nl,
|
|
print_clause('WHERE',Where,'AND'),
|
|
nl,
|
|
print_clause('GROUP BY',Group,',').
|
|
|
|
print_query(negated_existential_subquery(Select,From,Where)):-
|
|
write('NOT EXISTS'),
|
|
nl,
|
|
write('('),
|
|
print_clause('SELECT',Select,','),
|
|
nl,
|
|
print_clause('FROM',From,','),
|
|
nl,
|
|
print_clause('WHERE',Where,'AND'),
|
|
nl,
|
|
write(')').
|
|
|
|
|
|
|
|
|
|
% --- print_clause(Keyword,ClauseCode,Separator) ---------------------------------------
|
|
%
|
|
% with
|
|
% Keyword one of SELECT, FROM, WHERE, or GROUP BY,
|
|
% ClauseCode the code corresponding to the appropriate clause of an SQL query, and
|
|
% Separator indicating the character(s) through which the items of a clause
|
|
% are separated from each other (',' or 'AND').
|
|
%
|
|
% --------------------------------------------------------------------------------------
|
|
|
|
% ILP
|
|
% print_clause(Keyword,[],_).
|
|
print_clause(_,[],_).
|
|
|
|
print_clause(Keyword,[Column|RestColumns],Separator):-
|
|
write(Keyword),
|
|
write(' '),
|
|
print_clause([Column|RestColumns],Separator).
|
|
|
|
print_clause(Keyword,Function,[Column],Separator):-
|
|
write(Keyword),
|
|
write(' '),
|
|
write(Function),
|
|
write('('),
|
|
print_clause([Column],Separator),
|
|
write(')').
|
|
|
|
|
|
|
|
|
|
|
|
% --- print_clause(ClauseCode,Separator) -----------------------------------------------
|
|
|
|
print_clause([Item],_):-
|
|
print_column(Item).
|
|
|
|
print_clause([Item,NextItem|RestItems],Separator):-
|
|
print_column(Item),
|
|
write(' '),
|
|
write(Separator),
|
|
write(' '),
|
|
print_clause([NextItem|RestItems],Separator).
|
|
|
|
|
|
|
|
|
|
% --- print_column(ColumnCode) --------------------------------
|
|
|
|
print_column('*'):-
|
|
write('*').
|
|
|
|
print_column(att(RangeVar,Attribute)):-
|
|
write(RangeVar),
|
|
write('.'),
|
|
write(Attribute).
|
|
|
|
print_column(rel(Relation,RangeVar)):-
|
|
write(Relation),
|
|
write(' '),
|
|
write(RangeVar).
|
|
|
|
print_column('$const$'(String)):-
|
|
get_type('$const$'(String),string),
|
|
write('"'),
|
|
write(String),
|
|
write('"').
|
|
|
|
print_column('$const$'(Number)):-
|
|
get_type('$const$'(Number),NumType),
|
|
type_compatible(NumType,number),
|
|
write(Number).
|
|
|
|
print_column(comp(LeftArg,Operator,RightArg)):-
|
|
print_column(LeftArg),
|
|
write(' '),
|
|
write(Operator),
|
|
write(' '),
|
|
print_column(RightArg).
|
|
|
|
print_column(LeftExpr * RightExpr):-
|
|
print_column(LeftExpr),
|
|
write('*'),
|
|
print_column(RightExpr).
|
|
|
|
print_column(LeftExpr / RightExpr):-
|
|
print_column(LeftExpr),
|
|
write('/'),
|
|
print_column(RightExpr).
|
|
|
|
print_column(LeftExpr + RightExpr):-
|
|
print_column(LeftExpr),
|
|
write('+'),
|
|
print_column(RightExpr).
|
|
|
|
print_column(LeftExpr - RightExpr):-
|
|
print_column(LeftExpr),
|
|
write('-'),
|
|
print_column(RightExpr).
|
|
|
|
print_column(agg_query(Function,Select,From,Where,Group)):-
|
|
nl,
|
|
write('('),
|
|
print_query(agg_query(Function,Select,From,Where,Group)),
|
|
write(')').
|
|
|
|
print_column(negated_existential_subquery(Select,From,Where)):-
|
|
print_query(negated_existential_subquery(Select,From,Where)).
|
|
|
|
|
|
|
|
|
|
|
|
% --- queries_atom(Queries,QueryAtom) ----------------------------
|
|
%
|
|
% queries_atom(Queries,QueryAtom) returns in its second argument
|
|
% the SQL query as a Prolog atom. For efficiency reasons, a list
|
|
% of ASCII codes is ceated as a difference list, and it is then
|
|
% transformed to an atom by name/2
|
|
% ----------------------------------------------------------------
|
|
|
|
|
|
queries_atom(Queries,QueryAtom):-
|
|
queries_atom(Queries,QueryList,[]),
|
|
name(QueryAtom,QueryList).
|
|
|
|
|
|
|
|
queries_atom([Query],QueryList,Diff):-
|
|
query_atom(Query,QueryList,Diff).
|
|
|
|
queries_atom([Query|Queries],QueryList,Diff):-
|
|
Queries \= [],
|
|
query_atom(Query,QueryList,X1),
|
|
column_atom('UNION',X1,X2),
|
|
queries_atom(Queries,X2,Diff).
|
|
|
|
|
|
|
|
% --- query_atom(QueryCode) --------------------------------
|
|
|
|
query_atom(query([agg_query(Function,Select,From,Where,Group)],_,_),QueryList,Diff):-
|
|
% --- ugly rule here: aggregate function only in SELECT Part of query ----
|
|
!,
|
|
query_atom(agg_query(Function,Select,From,Where,Group),QueryList,Diff).
|
|
|
|
query_atom(query(Select,From,Where),QueryList,Diff):-
|
|
clause_atom('SELECT',Select,',',QueryList,X1),
|
|
clause_atom('FROM',From,',',X1,X2),
|
|
clause_atom('WHERE',Where,'AND',X2,Diff).
|
|
|
|
query_atom(agg_query(Function,Select,From,Where,Group),QueryList,Diff):-
|
|
clause_atom('SELECT',Function,Select,',',QueryList,X1),
|
|
clause_atom('FROM',From,',',X1,X2),
|
|
clause_atom('WHERE',Where,'AND',X2,X3),
|
|
clause_atom('GROUP BY',Group,',',X3,Diff).
|
|
|
|
query_atom(negated_existential_subquery(Select,From,Where),QueryList,Diff):-
|
|
column_atom('NOT EXISTS(',QueryList,X1),
|
|
clause_atom('SELECT',Select,',',X1,X2),
|
|
clause_atom('FROM',From,',',X2,X3),
|
|
clause_atom('WHERE',Where,'AND',X3,X4),
|
|
column_atom(')',X4,Diff).
|
|
|
|
|
|
|
|
|
|
% --- clause_atom(Keyword,ClauseCode,Junctor,CurrAtom,QueryAtom) -------------
|
|
%
|
|
% with
|
|
% Keyword one of SELECT, FROM, WHERE, or GROUP BY,
|
|
% ClauseCode the code corresponding to the appropriate clause of an SQL query, and
|
|
% Junctor indicating the character(s) through which the items of a clause
|
|
% are separated from each other (',' or 'AND').
|
|
|
|
% ILP
|
|
% clause_atom(Keyword,[],_,QueryList,QueryList).
|
|
clause_atom(_,[],_,QueryList,QueryList).
|
|
|
|
clause_atom(Keyword,[Column|RestColumns],Junctor,QueryList,Diff):-
|
|
column_atom(Keyword,QueryList,X1),
|
|
column_atom(' ',X1,X2),
|
|
clause_atom([Column|RestColumns],Junctor,X2,X3),
|
|
column_atom(' ',X3,Diff).
|
|
|
|
%DISTINCT
|
|
clause_atom(Keyword,'COUNTDISTINCT',[Column],Junctor,QueryList,Diff):-!,
|
|
column_atom(Keyword,QueryList,X1),
|
|
column_atom(' ',X1,X2),
|
|
column_atom('COUNT',X2,X3),
|
|
column_atom('(DISTINCT ',X3,X4),
|
|
clause_atom([Column],Junctor,X4,X5),
|
|
column_atom(') ',X5,Diff).
|
|
|
|
clause_atom(Keyword,Function,[Column],Junctor,QueryList,Diff):-
|
|
column_atom(Keyword,QueryList,X1),
|
|
column_atom(' ',X1,X2),
|
|
column_atom(Function,X2,X3),
|
|
column_atom('(',X3,X4),
|
|
clause_atom([Column],Junctor,X4,X5),
|
|
column_atom(') ',X5,Diff).
|
|
|
|
|
|
|
|
|
|
|
|
|
|
% --- clause_atom(ClauseCode,Junctor) --------------------------------
|
|
|
|
clause_atom([Item],_,QueryList,Diff):-
|
|
column_atom(Item,QueryList,Diff).
|
|
|
|
clause_atom([Item,NextItem|RestItems],Junctor,QueryList,Diff):-
|
|
column_atom(Item,QueryList,X1),
|
|
column_atom(' ',X1,X2),
|
|
column_atom(Junctor,X2,X3),
|
|
column_atom(' ',X3,X4),
|
|
clause_atom([NextItem|RestItems],Junctor,X4,Diff).
|
|
|
|
|
|
|
|
|
|
|
|
column_atom(att(RangeVar,Attribute),QueryList,Diff):-
|
|
column_atom(RangeVar,QueryList,X1),
|
|
column_atom('.',X1,X2),
|
|
column_atom(Attribute,X2,Diff).
|
|
|
|
column_atom(rel(Relation,RangeVar),QueryList,Diff):-
|
|
column_atom(Relation,QueryList,X1),
|
|
column_atom(' ',X1,X2),
|
|
column_atom(RangeVar,X2,Diff).
|
|
|
|
column_atom('$const$'(String),QueryList,Diff):-
|
|
get_type('$const$'(String),string),
|
|
column_atom('"',QueryList,X1),
|
|
column_atom(String,X1,X2),
|
|
column_atom('"',X2,Diff).
|
|
|
|
column_atom('$const$'(Number),QueryList,Diff):-
|
|
get_type('$const$'(Number),NumType),
|
|
type_compatible(NumType,number),
|
|
column_atom(Number,QueryList,Diff).
|
|
|
|
column_atom(comp(LeftArg,Operator,RightArg),QueryList,Diff):-
|
|
column_atom(LeftArg,QueryList,X1),
|
|
column_atom(' ',X1,X2),
|
|
column_atom(Operator,X2,X3),
|
|
column_atom(' ',X3,X4),
|
|
column_atom(RightArg,X4,Diff).
|
|
|
|
column_atom(LeftExpr * RightExpr,QueryList,Diff):-
|
|
column_atom(LeftExpr,QueryList,X1),
|
|
column_atom('*',X1,X2),
|
|
column_atom(RightExpr,X2,Diff).
|
|
|
|
column_atom(LeftExpr + RightExpr,QueryList,Diff):-
|
|
column_atom(LeftExpr,QueryList,X1),
|
|
column_atom('+',X1,X2),
|
|
column_atom(RightExpr,X2,Diff).
|
|
|
|
column_atom(LeftExpr - RightExpr,QueryList,Diff):-
|
|
column_atom(LeftExpr,QueryList,X1),
|
|
column_atom('-',X1,X2),
|
|
column_atom(RightExpr,X2,Diff).
|
|
|
|
column_atom(LeftExpr / RightExpr,QueryList,Diff):-
|
|
column_atom(LeftExpr,QueryList,X1),
|
|
column_atom('/',X1,X2),
|
|
column_atom(RightExpr,X2,Diff).
|
|
|
|
column_atom(agg_query(Function,Select,From,Where,Group),QueryList,Diff):-
|
|
column_atom('(',QueryList,X1),
|
|
query_atom(agg_query(Function,Select,From,Where,Group),X1,X2),
|
|
column_atom(')',X2,Diff).
|
|
|
|
column_atom(negated_existential_subquery(Select,From,Where),QueryList,Diff):-
|
|
query_atom(negated_existential_subquery(Select,From,Where),QueryList,Diff).
|
|
|
|
|
|
column_atom(Atom,List,Diff):-
|
|
atom(Atom),
|
|
name(Atom,X1),
|
|
append(X1,Diff,List).
|
|
|
|
column_atom(Number,List,Diff) :-
|
|
number(Number),
|
|
name(Number,X1),
|
|
append(X1,Diff,List).
|
|
|
|
|
|
|
|
% --- gensym(Root,Symbol) ----------------------------------------------------
|
|
%
|
|
% SEPIA 3.2. version - other Prolog implementations provide gensym/2
|
|
% and init_gensym/1 as built-ins. */
|
|
%
|
|
% (C) Christoph Draxler, Aug. 1992
|
|
%
|
|
%
|
|
|
|
init_gensym(Atom) :-
|
|
set_value(Atom,'@').
|
|
|
|
gensym(Atom,Var) :-
|
|
var(Var),
|
|
get_value(Atom,Value),
|
|
char_code(Value,Code),
|
|
NewCode is Code + 1,
|
|
char_code(Var,NewCode),
|
|
set_value(Atom,Var).
|
|
|
|
|
|
|
|
% --- auxiliary predicates (some of them may be built-in... --------------------
|
|
|
|
append([],L,L).
|
|
append([H1|L1],L2,[H1|L3]):-
|
|
append(L1,L2,L3).
|
|
|
|
|
|
|
|
member(X,[X|_]).
|
|
member(X,[_|T]):-
|
|
member(X,T).
|
|
|
|
|
|
|
|
repeat_n(N):-
|
|
integer(N),
|
|
N > 0,
|
|
repeat_1(N).
|
|
|
|
repeat_1(1):-!.
|
|
repeat_1(_).
|
|
repeat_1(N):-
|
|
N1 is N-1,
|
|
repeat_1(N1).
|
|
|
|
|
|
|
|
% --- set_difference(SetA,SetB,Difference) --------------------------------------------
|
|
%
|
|
% SetA - SetB = Difference
|
|
|
|
set_difference([],_,[]).
|
|
|
|
set_difference([Element|RestSet],Set,[Element|RestDifference]):-
|
|
not member(Element,Set),
|
|
set_difference(RestSet,Set,RestDifference).
|
|
|
|
set_difference([Element|RestSet],Set,RestDifference):-
|
|
member(Element,Set),
|
|
set_difference(RestSet,Set,RestDifference).
|
|
|
|
|
|
|
|
% % --- benchmarking programs --------------------------------------------
|
|
% %
|
|
% % taken from R. O'Keefe: The Craft of Prolog, MIT Press 1990
|
|
% %
|
|
% % Sepia Prolog version
|
|
|
|
% cpu_time(Time):-
|
|
% cputime(Time).
|
|
|
|
|
|
% cpu_time(Goal,Duration):-
|
|
% !,
|
|
% cputime(T1),
|
|
% (call(Goal) -> true; true),
|
|
% cputime(T2),
|
|
% Duration is T2 - T1.
|
|
|
|
% cpu_time(N,Goal,Duration):-
|
|
% !,
|
|
% cpu_time((repeat_n(N),(Goal -> fail);true),D1),
|
|
% cpu_time((repeat_n(N),(true -> fail);true),D2),
|
|
% Duration is D1 - D2.
|
|
|
|
|
|
|
|
|
|
% % --- benchmarks of sample queries ---------
|
|
|
|
% benchmark(N,1,D):-
|
|
% cpu_time(N,
|
|
% (translate(flight(No,Dep,Dest,Type),flight(No,Dep,Dest,Type),Code),
|
|
% printqueries(Code)),
|
|
% D).
|
|
|
|
% benchmark(N,2,D):-
|
|
% cpu_time(N,
|
|
% (translate(capacity(No,Dep,Dest,Type,Seats),
|
|
% (flight(No,Dep,Dest,Type),
|
|
% plane(Type,Seats),
|
|
% Type='b-737'),Code),
|
|
% printqueries(Code)),
|
|
% D).
|
|
|
|
% benchmark(N,3,D):-
|
|
% cpu_time(N,
|
|
% (translate(no_planes(No,Dep,Dest,Type),
|
|
% (flight(No,Dep,Dest,Type),
|
|
% not plane(Type,Seats)),Code),
|
|
% printqueries(Code)),
|
|
% D).
|
|
|
|
% benchmark(N,4,D):-
|
|
% cpu_time(N,(translate(X,X is count(S,plane(P,S)),Code),printqueries(Code)),D).
|
|
|
|
% benchmark(N,5,D):-
|
|
% cpu_time(N,
|
|
% (translate(big_planes(munich,Dest,Type,Seats),
|
|
% FNo^(flight(FNo,munich,Dest,Type),
|
|
% plane(Type,Seats),
|
|
% Seats > avg(S, T^plane(T,S))),Code),
|
|
% printqueries(Code)),
|
|
% D).
|
|
|
|
% benchmark(N,6,D):-
|
|
% cpu_time(N,(
|
|
% translate(big_planes(munich,Dest,Type,Seats),
|
|
% FNo^(flight(FNo,munich,Dest,Type),
|
|
% plane(Type,Seats),
|
|
% Seats > avg(S, T^plane(T,S))),Code),
|
|
% printqueries(Code)),
|
|
% D).
|
|
|
|
% benchmark(N,7,D):-
|
|
% cpu_time(N,(
|
|
% translate(big_planes(munich,Dest,Type,Seats),
|
|
% FNo^(flight(FNo,munich,Dest,Type),
|
|
% plane(Type,Seats),
|
|
% Seats > avg(S, T^plane(T,S))),Code),
|
|
% queries_atom(Code,SQLQueryAtom),
|
|
% writeq(query_atom(SQLQueryAtom)),
|
|
% nl),
|
|
% D).
|
|
|
|
|
|
|
|
|
|
|
|
% % --- Meta Database for schema definition of SQL DB in Prolog --------------------------
|
|
% %
|
|
% % maps Prolog predicates to SQL table names, Prolog predicate argument positions to SQL
|
|
% % attributes, and Prolog operators to SQL operators.
|
|
% %
|
|
% % ATTENTION! It is assumed that the arithmetic operators in Prolog and SQL are the same,
|
|
% % i.e. + is addition in Prolog and in SQL, etc. If this is not the case, then a mapping
|
|
% % function for arithmetic operators is necessary too.
|
|
% % --------------------------------------------------------------------------------------
|
|
|
|
|
|
% % --- relation(PrologFunctor,Arity,SQLTableName) ---------------------------------------
|
|
|
|
% relation(flight,4,'FLIGHT').
|
|
% relation(plane,2,'PLANE').
|
|
|
|
|
|
% % --- attribute(PrologArgumentPosition,SQLTableName,SQLAttributeName) ------------------
|
|
|
|
% attribute(1,'FLIGHT','FLIGHT_NO',string).
|
|
% attribute(2,'FLIGHT','DEPARTURE',string).
|
|
% attribute(3,'FLIGHT','DESTINATION',string).
|
|
% attribute(4,'FLIGHT','PLANE_TYPE',string).
|
|
|
|
|
|
% attribute(1,'PLANE','TYPE',string).
|
|
% attribute(2,'PLANE','SEATS',integer).
|
|
|
|
|
|
% --- Mapping of Prolog operators to SQL operators -------------------------------------
|
|
|
|
comparison(=,=).
|
|
comparison(<,<).
|
|
comparison(>,>).
|
|
comparison(@<,<).
|
|
comparison(@>,>).
|
|
|
|
|
|
negated_comparison(=,'<>').
|
|
negated_comparison(\=,=).
|
|
negated_comparison(>,=<).
|
|
negated_comparison(=<,>).
|
|
negated_comparison(<,>=).
|
|
negated_comparison(>=,<).
|
|
|
|
|
|
% --- aggregate_function(PrologFunctor,SQLFunction) -----------------
|
|
|
|
aggregate_functor(avg,'AVG').
|
|
aggregate_functor(min,'MIN').
|
|
aggregate_functor(max,'MAX').
|
|
aggregate_functor(sum,'SUM').
|
|
aggregate_functor(count,'COUNT').
|
|
aggregate_functor(countdistinct,'COUNTDISTINCT').
|
|
|
|
|
|
|
|
% --- type system --------------------------------------------------------------
|
|
%
|
|
% A rudimentary type system is provided for consistency checking during the
|
|
% translation and for output formatting
|
|
%
|
|
% The basic types are string and number. number has the subtypes integer and
|
|
% real.
|
|
%
|
|
% ------------------------------------------------------------------------------
|
|
|
|
|
|
type_compatible(Type,Type):-
|
|
is_type(Type).
|
|
type_compatible(SubType,Type):-
|
|
subtype(SubType,Type).
|
|
type_compatible(Type,SubType):-
|
|
subtype(SubType,Type).
|
|
|
|
|
|
% --- subtype(SubType,SuperType) -----------------------------------------------
|
|
%
|
|
% Simple type hierarchy checking
|
|
%
|
|
% ------------------------------------------------------------------------------
|
|
|
|
subtype(SubType,SuperType):-
|
|
is_subtype(SubType,SuperType).
|
|
|
|
subtype(SubType,SuperType):-
|
|
is_subtype(SubType,InterType),
|
|
subtype(InterType,SuperType).
|
|
|
|
|
|
|
|
% --- is_type(Type) ------------------------------------------------------------
|
|
%
|
|
% Type names
|
|
%
|
|
% ------------------------------------------------------------------------------
|
|
|
|
is_type(number).
|
|
is_type(integer).
|
|
is_type(real).
|
|
is_type(string).
|
|
is_type(natural).
|
|
|
|
|
|
% --- is_subtype(SubType,SuperType) --------------------------------------------
|
|
%
|
|
% Simple type hierarchy for numeric types
|
|
%
|
|
% ------------------------------------------------------------------------------
|
|
|
|
is_subtype(integer,number).
|
|
is_subtype(real,number).
|
|
is_subtype(natural,integer).
|
|
|
|
|
|
% --- get_type(Constant,Type) --------------------------------------------------
|
|
%
|
|
% Prolog implementation specific definition of type retrieval
|
|
% sepia Prolog version given here
|
|
%
|
|
% ------------------------------------------------------------------------------
|
|
|
|
get_type('$const$'(Constant),integer):-
|
|
integer(Constant),!.
|
|
|
|
get_type('$const$'(Constant),real):-
|
|
number(Constant),!.
|
|
|
|
get_type('$const$'(Constant),string):-
|
|
atom(Constant).
|