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Request for help on retrieving binary data from bytea column using ODBC calls

From: Ganesh Borse <bganesh05(at)gmail(dot)com>
To: pgsql-odbc(at)postgresql(dot)org
Subject: Request for help on retrieving binary data from bytea column using ODBC calls
Date: 2012-02-24 05:06:34
Message-ID: CAEhYC0HOec=cZQG6C3HWAWNGR8R-dhrdtQwH2xBhdW8AuHG1XA@mail.gmail.com (view raw or flat)
Thread:
Lists: pgsql-odbc
Dear All,

I've a VC++ application which displays the various binary files (like jpgs,
xls, zips) stored in PostgrelSQL DB in bytea column.
Files are inserted into bytea column using hex encoding.

But, when I try to access this column by executing the query "select * from
tablename;" from ODBC on Windows in this application, the buffer contains
the same hex encoded data, but not the binary data.

Application does the following steps to retrieve this binary data. This
same code works well with other DBS, like Oracle, Sybase, DB2, MSSQL & so
on.
//---------------------------------------------------------------------------------------------------
// prepare query:
wchar_t *query = _T("select * from mytable;");
   SQLRETURN ret = SQLPrepare(stmt, query, SQL_NTS);
   if (!SQL_SUCCEEDED(ret))
   {
      TRACE("SybAse:SQLprepare failed.");
      DbException::sqlErrorInfo(SQL_HANDLE_STMT, stmt);
      throw DbException(std::string(""));
   }
// bind to column:
   SQLBindCol(stmtHdl, columnNumber, SQL_C_BINARY,
             m_colValue[0], m_len, &m_LenInd[0]);
// Execute query:
ret = SQLExecute(stmt);
// fetch rows
if (SQL_SUCCESS == ret || SQL_SUCCESS_WITH_INFO == ret)
{
   do {
      ret = SQLFetchScroll(m_stmt, SQL_FETCH_NEXT, 0);
      // handle data per row here...
   } while(SQL_SUCCEEDED(ret));
}
//---------------------------------------------------------------------------------------------------

Can you please help me know, how can I retrieve the data stored in bytea
columns in binary format, so that those file can be handled appropriately?

Thanks in advance for your help and guidance.

Best Regards,
Ganesh

Responses

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Next:From: Hiroshi InoueDate: 2012-02-24 09:06:01
Subject: Re: Request for help on retrieving binary data from bytea column using ODBC calls
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Subject: Re: psqlODBC driver version compatibility with PostgreSQL database

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