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<td align="left"> <A href="Param_Usage.html" style="TEXT-DECORATION: none"><h3>Usage</h3></A>
</td>
<td align="left"> <A href="Param.html" style="TEXT-DECORATION: none"><h3>Class Members</h3></A>
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<td align="left"> <A href="Param_Examples.html" style="TEXT-DECORATION: none"><h3>Examples</h3></A>
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<td colspan="3"><h1>SAParam::ReadLongOrLob</h1></td>
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<p><font face="Arial"><STRONG>void
ReadLongOrLob(</STRONG> <STRONG>saLongOrLobReader_t</STRONG>
fnReader,
<STRONG>unsigned int</STRONG>
nReaderWantedPieceSize, <STRONG>void
*</STRONG>pAddlData <STRONG> );<BR>throw
(SAException);</STRONG></font></p>
<p>
Starts reading of Long
or BLob(CLob) value using user defined
callback.
</p>
<P>
<H3>Parameters</H3>
<P><EM>fnReader</EM>. The name of user function
used for Long or BLob(CLob) data reading. The function must have
syntax declared by <A
href="Enums.html#saLongOrLobReader_t">saLongOrLobReader_t
typedef</A>
.</P>
<P><EM>nReaderWantedPieceSize</EM>. Size of piece
of data user want to get to callback function.</P>
<P><EM>pAddData</EM>. Additional data, passed to
callback function. </P>
<H3>Remarks</H3>
<P>
After
a command execution all output parameters are updated by their
values, including Long and BLob(CLob) parameters. If you want to
control piecewise reading of Long or BLob(CLob) data you should do
the following:</P>
<OL>
<LI>Before a command execution set <STRONG
>SA_LongOrLobReaderManual</STRONG>
reading
mode (see <A href="ValueRead_setLongOrLobReaderMode.html" >setLongOrLobReaderMode</A>)
for Long or BLob(CLob) parameters you want to process by user
defined function(s). After that each
fetch will
skip reading Long and BLob(CLob) parameters that you set to be
read manually.
<LI>After a command
execution use
<STRONG>ReadLongOrLob</STRONG>
method for
each parameter defined to be read manually.</LI></OL>
<P>Note, that if the command has result set(s)
(it is possible in some servers, see <STRONG>Server specific
notes</STRONG> ) then output
parameters are available only after all result sets are completely
processed using <A href="Command_FetchNext.html" >SACommand::FetchNext</A>
method.</P>
<P><STRONG>ReadLongOrLob</STRONG>
method will repeatedly call user
defined function:</P>
<P><FONT face=System>void <function
Name>(SAPieceType_t ePieceType, <BR>
void *pBuf, <BR>
unsigned int nLen, <BR>
unsigned int nBlobSize, <BR>
void *pAddlData);</FONT></P>
<P>User
defined function has the following parameters:</P>
<P><EM>ePieceType</EM>. Parameter passed to the
function from SQLAPI++ Library mechanisms. It defines which
piece of data value was read. Can be one of the next <STRONG
>SAPieceType_t</STRONG>
enum values:</P>
<UL>
<LI><STRONG>SA_FirstPiece</STRONG> The first (but
not the last) piece of data was read.
<LI><STRONG>SA_NextPiece</STRONG> The next (not the
first and not the last) piece of data was read.
<LI><STRONG>SA_LastPiece</STRONG> The last piece of
data was read.
<LI><STRONG>SA_OnePiece</STRONG> All parameter data
was read as one block.</LI></UL>
<P><EM>pBuf</EM>. Pointer to the buffer that
contains the data block read from database.</P>
<P><EM>nLen</EM>. The actual size of data in buffer
<EM>pBuf</EM>.</P>
<P><EM>nBlobSize</EM>. A size of whole Long or
BLob(CLob) parameter (if DBMS server allows to know it before whole
parameter was read; otherwise 0).</P>
<P><EM>pAddData</EM>. An additional data user want
to pass to the function.</P>
<P>To get more information about reading Long
and BLob(CLob) data see <A href="../Examples/step6.cpp" >Query examples - Step
6</A>. </P>
<P></P>
<h3>Server specific notes</h3>
<P>See <A
href="../ServerSpecific/index.html">Server specific information</A>
concerning your SQL server.</P>
<h3>Problems and Questions</h3>
<p> If
you don't find the answer to you questions or
have some problems on using the Library, please, send e-mail to <A href="mailto:howto@sqlapi.com">howto@sqlapi.com</A>.
</p>
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