Re: How to deal with LOBs in C++

rbanerji_at_icfkaiser.com wrote:
>
> I need to open a BFILE, read its contents into a BLOB and then access this
> blob in C++ code.
>
> How can this be done? Will I have to use Pro C? Is there any other way?
>
> What is the API, DBMS_LOB packake, and OCI? What are some good references for
> these features? Will any one of them be useful in what I need to do?
>
> I am not an Oracle programmer. Until now I have simply been sending in SQLs
> to the Oracle DBMS.
>
> Thanks,
>
If you want to access LOBs from C++ you need to write either a Pro C or OCI - Programm.
With Pro C one writes a *.pc - file with C/C++ - Code and embedded SQL-Statements.
The Pro C - Precompiler takes this *.pc file and generates a valid *.cpp file that contains
data structures and calls to the sqllib. The advantage of Pro C is that establishing
a connection and getting started is pretty uncomplicated.

The Oracle Call Interface is a library that allows interaction with the Oracle DBMS.
Preparing SQL-Statments and Binding In- and Output-Variables is more work than with Pro C.
In OCI there are functions like OCILobRead(), OCILobWrite() and OCILobGetLength().
You don't necessarily need the DBMS_LOB Package. The advantage of OCI is that there is no extra precompile step. This makes IMHO debugging and development easier.

There are a few example files in the ORACLE OCI-Dokumentation and on the Oracle Technology network http://technet.oracle.com/.

With C++, as opposed with C, you might have to change the typedef text to OraText in
the OCI header files. text is used by the IOstreams of the standard library.
You might also want to take a look at:
  http://home.sprynet.com/sprynet/skuchin/otl_1pg.htm . This is a class that is a wrapper around OCI-calls. I don't know wether it supports LOBs.

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  * \author Bernhard.Schmalhofer_at_fuzzy-online.de
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