Re: defining a variable to hold LONG field using OCI

From: Thomas Kyte <tkyte_at_us.oracle.com>
Date: Wed, 18 Nov 1998 17:33:17 GMT
Message-ID: <3658047b.15927973@192.86.155.100>

A copy of this was sent to shaih_at_NoSpaMinter.net.il (Shaya) (if that email address didn't require changing) On Wed, 18 Nov 1998 14:52:16 GMT, you wrote:

>Hi All
>I'm using Oracle 7.3 and I'm trying to work with LONG fields.
>
>How can I get the actual size of the data in a long field before I use
>the odefin() so I don't have to allocate all 2^32 (max size)?
>
>My LONG field needs to get sometimes a data length of over 2000 bytes
>(up to 100M) , but most of the times it is much shorter (under 1024
>bytes) is there some other type I can use to hold it?
>
>Thanks in advance
>Shaya
>Remove the NoSpaM from my e-mail address to reply

you could piecewise fetch the data. Here is a quick example. this function expects a sql statement that fetches 2 columns -- column 1 is a long raw and column2 is the name of a file to open and write the long raw to (change the odefin call to bind a datatype = 8 instead of 24 to allow this to work for LONGS)...

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#include "unload.h"

void save_images( char * sql_statement ) {
ub1 * ucp;
int UCP_SIZE = 65536;

sb2      indp = 0;
sb2      indp2 = 0;
ub4      ret_len = 0;
ub2      retl = 0;
ub2      retl2 = 0;
ub2      rcode = 0;
ub2      rcode2 = 0;
int      fetched;
text     file_name[255];
FILE     * output;
int     rc;

    ucp = (ub1 *)malloc( UCP_SIZE );
    if ( !ucp )
    {

        printf(  "Unable to allocate %d bytes", UCP_SIZE );
        exit(1);

    }

    if (oparse(&cda, sql_statement, -1, 0, 2))     {

        printf( oerr_cda() );
        exit(1);

    }

    if (odefin(&cda, 1, ucp, UCP_SIZE, 24, -1,     /* if (odefin(&cda, 1, ucp, UCP_SIZE, 8, -1, */

               &indp, (text *) 0, 0, -1, &retl, &rcode))     {

       printf( "Error binding column1\n" );
       printf(oerr_cda());
       fflush( stdout );
       exit(1);

    }
    if (odefin(&cda, 2, file_name, sizeof(file_name), STRING_TYPE, -1,

               &indp2, (text *) 0, 0, -1, &retl2, &rcode2))     {

       printf( "Error binding column2\n" );
       printf(oerr_cda());
       exit(1);

    }

    for( rc = oexfet(&cda, (ub4) 1, 0, 0); !rc; rc = ofetch(&cda) )     {

        output = fopen( file_name, "wb" );
        if ( output == NULL )
        {
            perror( "fopen" );
            printf( "failed to open %s\n", file_name );
            exit(1);
        }
        for( fetched = 0, ret_len = 1; ret_len; fetched += ret_len )
        {
            if (oflng(&cda, 1, ucp, UCP_SIZE,
                        24, &ret_len, fetched ))
                        /* 8, &ret_len, fetched ))  */
            {
                printf(oerr_cda());
                exit(1);
            }
            if ( ret_len )
            {
                if ( fwrite( ucp, 1, ret_len, output ) != ret_len )
                {
                    perror( "fwrite" );
                    printf( "Fwrite of %d bytes fails\n", (int)ret_len );
                    exit(1);
                }
            }
        }
        fclose( output );
        printf( "Wrote File %s with %d bytes\n", file_name, fetched );

    }
}  

Thomas Kyte
tkyte_at_us.oracle.com
Oracle Government
Herndon VA

--
http://govt.us.oracle.com/ -- downloadable utilities  

---

Opinions are mine and do not necessarily reflect those of Oracle Corporation  

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