IldAppDescriptor Class Reference

Instances of the class IldAppDescriptor hold the description of a column or a parameter, the size of the data buffer, and the addresses of the data and null indicator buffers. More...

#include <ildblink/ildtuple.h>

Inheritance diagram for IldAppDescriptor:

Public Member Functions
IlUInt	getBufferSize () const
	Get the maximum size of the values. More...
short *	getNulls () const
	Get the null indicators buffer. More...
char *	getValue (IlUInt r=0) const
	Get the value buffer. More...
IlBoolean	isExtNulls () const
	Tell if the null indicators buffer is externally allocated. More...
IlBoolean	isExtValue () const
	Tell if the buffer is externally managed. More...
void	setBufferSize (IlUInt size)
	Set the actual size of the values buffer. More...
void	setNulls (short *nulls, IlBoolean ext=IlFalse)
	Change the null-indicators buffer of the descriptor. More...
void	setValue (char *v, IlBoolean ext=IlFalse)
	Change the data buffer of the descriptor. More...
Public Member Functions inherited from IldDescriptor
IldADTDescriptor *	getADTDescriptor () const
	Get the abstract data type descriptor. More...
const char *	getName () const
	Get the name of the described object. More...
short	getPrecision () const
	Get the precision of the described object. More...
short	getScale () const
	Get the scale of the described object. More...
IlUInt	getSize () const
	Get the maximum data size of the described object. More...
short	getSqlType () const
	Get the SQL type of the decribed object. More...
const char *	getSqlTypeName () const
	Get the SQL type name of the described object. More...
IldColumnType	getType () const
	Get the type of the described object. More...
IlBoolean	isNullable () const
	Indicates whether or not the column can contain values that are NULL in the RDBMS sense.

Detailed Description

Instances of the class IldAppDescriptor hold the description of a column or a parameter, the size of the data buffer, and the addresses of the data and null indicator buffers.

Library: dbkernel

The descriptors of a result set are built during the parse step if the statement is prepared, or during the execute step if the statement is executed immediately (see the member functions IldRequest::parse and IldRequest::execute).

The descriptors of a parameters set are built at bind time for RDBMSs that do not have the "describe parameter" capability, and at prepare time for the other RDBMSs (see the member functions IldRequest::bindParam and IldRequest::parse).

See also

IldDescriptor, IldRequest

Member Function Documentation

getBufferSize()

IlUInt IldAppDescriptor::getBufferSize

(

)

const

Get the maximum size of the values.

Returns

The size of the values buffer in bytes.

Note

Right after creation of the instance, the buffer is not allocated, thus its size is 0.

getNulls()

short * IldAppDescriptor::getNulls

(

)

const

Get the null indicators buffer.

Returns

The current null-indicators buffer.

Note

Right after creation of the instance, the nulls buffer is not allocated.

getValue()

char* IldAppDescriptor::getValue

(

IlUInt

r = 0

)

const

Get the value buffer.

Parameters

r	The row index.

Returns

The value buffer corresponding to the row r in the rows set.

Note

The given row index is not checked by this function. It is the application responsibility to ensure this index is smaller that the number of rows in the column or parameter set.

See also

IldRequest::getColArraySize, IldRequest::getParamArraySize.

isExtNulls()

IlBoolean IldAppDescriptor::isExtNulls

(

)

const

Tell if the null indicators buffer is externally allocated.

Returns

IlFalse if the null-indicators buffer was allocated by DB Link, or IlTrue if the buffer was allocated by an external application.

Note

Right after creation of the instance, the nulls buffer is not allocated, thus is considered as externally allocated.

isExtValue()

IlBoolean IldAppDescriptor::isExtValue

(

)

const

Tell if the buffer is externally managed.

Returns

IlFalse if the values buffer was allocated by DB Link, or IlTrue if the buffer was allocated by an external application.

Note

Right after creation of the instance, the buffer is not allocated and thus is considered as been externally allocated.

setBufferSize()

void IldAppDescriptor::setBufferSize

(

IlUInt

size

)

Set the actual size of the values buffer.

Parameters

size	The maximum size, in bytes, of the data for one value.

The application must ensure that the parameter size is not smaller than the actual size of the buffer. While this function will accept such a value, the error ILD_BAD_VARIABLE_SIZE could be raised at bind time.

If the buffer size is changed after bindings have been processed or in between fetches, the behavior of the application is unpredictable.

Warning

Never use this function once the buffer is allocated by DB Link.

See also

IldRequest::bindCol, IldRequest::bindParam.

setNulls()

void IldAppDescriptor::setNulls	(	short *	nulls,
		IlBoolean	ext = IlFalse
	)

Change the null-indicators buffer of the descriptor.

Parameters

nulls	The new null indicators buffer.
ext	Optionally, is the buffer externally managed or managed by DB Link.

The second argument ext specifies the owner of the allocated buffer as follows:

• If the buffer was allocated by DB Link, its value is IlFalse,
• If the buffer was allocated by the application, its value is IlTrue. In this case, the buffer will not be deleted by DB Link when requests are cleaned up or deleted.

setValue()

void IldAppDescriptor::setValue	(	char *	v,
		IlBoolean	ext = IlFalse
	)

Change the data buffer of the descriptor.

Parameters

v	The new buffer to be used to store data.
ext	Optionally, is the buffer externally managed or managed by DB Link.

The second argument ext specifies the owner of the allocated buffer as follows:

• If the buffer was allocated by DB Link, its value is IlFalse.
• If the buffer was allocated by the application, its value is IlTrue. In this case, the buffer will not be deleted by DB Link when requests are cleaned up or deleted.