CoGaDB::SQL::ParseTree::ComparisonPredicate Struct Reference

#include <sql_parsetree.hpp>

Inheritance diagram for CoGaDB::SQL::ParseTree::ComparisonPredicate:

Collaboration diagram for CoGaDB::SQL::ParseTree::ComparisonPredicate:

List of all members.

Public Member Functions
	ComparisonPredicate (ScalarExpressionPtr _lvalue, ValueComparator _op, ScalarExpressionPtr _rvalue)
KNF_Selection_Expression	getCNF (TypedNodePtr &io_node)
	Get Conjunctive Normal Form of a search condition predicate.
Public Attributes
ScalarExpressionPtr	lvalue
ValueComparator	op
ScalarExpressionPtr	rvalue

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Constructor & Destructor Documentation

CoGaDB::SQL::ParseTree::ComparisonPredicate::ComparisonPredicate	(	ScalarExpressionPtr	_lvalue,
		ValueComparator	_op,
		ScalarExpressionPtr	_rvalue
	)		[inline]

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Member Function Documentation

KNF_Selection_Expression CoGaDB::SQL::ParseTree::ComparisonPredicate::getCNF

(

TypedNodePtr &

io_node

)

[virtual]

Get Conjunctive Normal Form of a search condition predicate.

Converting a single predicate to CNF is trivial - it is simply wrapped in a disjunction that is wrapped in a conjunction.

Since predicates in a CNF structure have their atomic type always on the right side of the operator (as in Column > Atom), the predicate operator might have to be flipped.

See also:

CoGaDB::Predicate

Parameters:

io_node

Reference to node pointer that holds the current chain of algebraic logical operators that is updated during CNF construction.

Returns:

CNF of parse tree predicate

map SQL comparison operators to CoGaDB's limited set of operators.

Todo:

If we would save the data type in the AtomExpression we could optimize expressions like (x >= 3) to (x > 2), saving one predicate.

Implements CoGaDB::SQL::ParseTree::SearchCondition.

References CoGaDB::KNF_Selection_Expression::disjunctions, CoGaDB::EQUAL, CoGaDB::GREATER, CoGaDB::GREATER_EQUAL, CoGaDB::LESSER, CoGaDB::LESSER_EQUAL, CoGaDB::SQL::ParseTree::make_pred(), CoGaDB::SQL::ParseTree::UNEQUAL, CoGaDB::ValueConstantPredicate, and CoGaDB::ValueValuePredicate.

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Member Data Documentation

ScalarExpressionPtr CoGaDB::SQL::ParseTree::ComparisonPredicate::lvalue

ValueComparator CoGaDB::SQL::ParseTree::ComparisonPredicate::op

ScalarExpressionPtr CoGaDB::SQL::ParseTree::ComparisonPredicate::rvalue

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The documentation for this struct was generated from the following files:

• /home/sebastian/gpudbms/trunk/cogadb/include/sql/server/sql_parsetree.hpp
• /home/sebastian/gpudbms/trunk/cogadb/src/sql/server/sql_parsetree.cpp