RWDBCriterion Class Reference
[Expressions]

Represents the result of applying logical operators to RWDBExpr. It is used to encapsulate SQL WHERE clauses. More...

#include <rw/db/expr.h>

Inheritance diagram for RWDBCriterion:

List of all members.

Public Member Functions
	RWDBCriterion (void)
	RWDBCriterion (const RWDBExpr &Left, RWDBPhraseBook::RWDBPhraseKey op, const RWDBExpr &Right)
	RWDBCriterion (RWDBPhraseBook::RWDBPhraseKey op, const RWDBExpr &expr)

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Detailed Description

RWDBCriterion is the result of applying logical operators to RWDBExpr. It is used to encapsulate SQL WHERE clauses.

RWDBCriterion represents a specialized type of RWDBExpr that is evaluated in an SQL statement as a boolean value. RWDBCriterion adds neither components nor member functions to the base class. Instead, it ensures that a nonboolean expression is not placed in a context that requires a boolean expression during compilation.

Synopsis

 #include <rw/db/expr.h>

Related Classes

RWDBCriterion is a special case of RWDBExpr. Please see RWDBExpr for details about RWDBCriterion usage, including operators and constructors.

Examples

In this example, an RWDBCriterion is created anonymously to be used as part of an SQL WHERE clause:

 int x = somevalue;
 RWDBSelector select = myDbase.selector();
 select.where(myTable["myColumn"] != x);

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Constructor & Destructor Documentation

RWDBCriterion::RWDBCriterion

(

void

)

The default constructor creates an empty criterion.

RWDBCriterion::RWDBCriterion	(	const RWDBExpr &	Left,
		RWDBPhraseBook::RWDBPhraseKey	op,
		const RWDBExpr &	Right
	)

Creates a dyadic RWDBCriterion from the Left and Right operands connected by the logical operator op.

RWDBCriterion::RWDBCriterion	(	RWDBPhraseBook::RWDBPhraseKey	op,
		const RWDBExpr &	expr
	)

Creates a monadic RWDBCriterion from the given op and expr.