RWDBAssignment

Module:  DB Interface Module   Group:  Expression Classes

                RWDBExpr
RWDBAssignment
                RWCollectable

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• Public Member Functions

Members

column()

expressions()

RWDBAssignment()

value()

#include <rw/db/expr.h>

RWDBAssignment is the result of applying the RWDBColumn::assign() method to an RWDBExpr. The result is an encapsulation of the SQL SET column = expression phrase, where column refers to the RWDBColumn instance whose assign() method produced the RWDBAssignment, and expression refers to its argument. RWDBAssignments are only used to build RWDBUpdaters.

This example adds the phrase SET name = `Joe' to an RWDBUpdater for the Names table. To do this, an RWDBAssignment instance is created anonymously:

RWDBTable Names = myDbase.table("Names");
RWDBUpdater update = Names.updater();
update << Names["name"].assign("Joe");

RWDBAssignment is a special case of RWDBExpr. See RWDBExpr for details.

RWDBAssignment instances are produced only by the assign() method of RWDBColumn.

RWDBAssignment();

Constructs a default RWDBAssignment. Provided only for convenience.

RWDBAssignment(const RWDBColumn& c, const RWDBValue& v);

Constructs an RWDBAssignment from an RWDBColumn and an RWDBValue. Self then emulates the SQL construct SET c=v.

RWDBAssignment(const RWDBColumn& c, const RWDBExpr& e);

Constructs an RWDBAssignment from an RWDBColumn and an RWDBExpr. Self then emulates the SQL construct SET c=e.

RWDBColumn 
column() const; 

Returns the RWDBColumn associated with self.

RWDBValue 
value() const; 

Returns the RWDBValue associated with self.

RWDBExpr 
expressions() const; 

Returns the RWDBExpr associated with self.

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