SourcePro® 2024.1 |
SourcePro® API Reference Guide |
Specialization of the base class RWDBCritFormDefinition used for defining SQL functions taking 1
parameter.
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#include <rw/db/func.h>
Public Member Functions | |
RWDBCritFuncDef1 (const RWCString &functionName) | |
virtual RWDBCriterion | operator() (const RWDBExpr &x1) |
Private Member Functions | |
virtual RWDBCriterion | operator() () |
virtual RWDBCriterion | operator() (const RWDBExpr &, const RWDBExpr &) |
virtual RWDBCriterion | operator() (const RWDBExpr &, const RWDBExpr &, const RWDBExpr &) |
virtual RWDBCriterion | operator() (const RWDBExpr &, const RWDBExpr &, const RWDBExpr &, const RWDBExpr &) |
Private Member Functions inherited from RWDBCritFormDefinition | |
RWDBCritFormDefinition () | |
RWDBCritFormDefinition (const RWCString &formatString) | |
RWDBCritFuncDef1 is a specialization of the base class RWDBCritFormDefinition. This class provides a simplified mechanism for defining SQL functions taking 1
parameter. Unlike the base class, this class does not require positional placeholders in its function definitions. Also, since the number of required parameters is fixed, compile-time checking can be done on the number of parameters actually passed.
RWDBExprFuncDef1 provides a parallel mechanism for defining an RWDBExpr, rather than using an RWDBCriterion.
The RWDBCritFormDefinition base class may be used directly to gain additional flexibility.
See RWDBCriterion for details on SQL WHERE
clauses in the DB Interface Module.
Imagine that a database vendor's SQL variant provides the boolean function VALID_NAME(string)
, which can be used in a WHERE
clause. The DB Interface Module has no direct support for this function, yet we would like to use it without losing the benefits of high-level constructs for data manipulation. To do so, we can use a function which we define ourselves:
Notice that the number of actual parameters passed to validName
is checked at compile time. Compare this with the example for RWDBCritFormDefinition.
RWDBCritFuncDef1::RWDBCritFuncDef1 | ( | const RWCString & | functionName | ) |
Creates an RWDBCritFuncDef1 for a functional expression that takes 1 parameter. After such an RWDBCritFuncDef1 is instantiated, functionName may be used as though it were a predefined function.
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privatevirtual |
Not applicable to this class. This class defines SQL functions taking one parameter.
Reimplemented from RWDBCritFormDefinition.
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privatevirtual |
Not applicable to this class. This class defines SQL functions taking one parameter.
Reimplemented from RWDBCritFormDefinition.
|
privatevirtual |
Not applicable to this class. This class defines SQL functions taking one parameter.
Reimplemented from RWDBCritFormDefinition.
|
privatevirtual |
Not applicable to this class. This class defines SQL functions taking one parameter.
Reimplemented from RWDBCritFormDefinition.
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virtual |
Returns an RWDBCriterion in the form of a function with 1 parameter whose name is the name that was passed to self's constructor.
Reimplemented from RWDBCritFormDefinition.
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