Classics Forum

Problem with BLOB: ESQL

Posted By: DBLRN DBLRN
Date: Sunday, 19 October 2003, at 5:40 a.m.

My Need:
---------------
I want to be able to read some BLOB fields (aprat from other non-BLOB ones) , using Dynamic SQL - i.e I want to be able to determine and field list at run-time.

Here is what have done:
------------------------
I have defined a SQL DESCRIPTOR and a cursor.
Have a locator structure for the BLOB Field.
The program during executoin fails with an err code of -450 [Locator Error], during the "FETCH" Command , when the BLOB field has some data in it.

Can you please help? I'm stuck with this ...
********Error encountered in FETCH ********
----------------------------------------------------------
SQLSTATE: IX000
SQLCODE: -450

- - - - - - - - - - - - - - - - - - - -
EXCEPTION 1: SQLSTATE=IX000
MESSAGE TEXT: Illegal ESQL locator, or uninitialized blob variable in
4GL.
CLASS ORIGIN: IX
SUBCLASS ORIGIN: IX000
----------------------------------------------------------


Here is the code snippet.
------------------------
My funtion begins here:

EXEC SQL BEGIN DECLARE SECTION;
int i;
int desc_count;
char demoquery[800];
char colname[19];
char result[ NAME_LEN + 1 ];
char queryvalue[4];
int ind;
loc_t blob_descr;
int fieldType;
EXEC SQL END DECLARE SECTION;

printf("DEMO Sample ESQL Program running.\n\n");
EXEC SQL WHENEVER ERROR STOP;

/* These next three lines have hard-wired both the query and
* the value for the parameter. This information could have
* been entered from the terminal and placed into the strings
* demoquery and a query value string (queryvalue), respectively.
*/


blob_descr.loc_loctype = LOCMEMORY;
blob_descr.loc_bufsize = -1;
blob_descr.loc_oflags = 0;
blob_descr.loc_mflags = 0;

sprintf(demoquery, "%s %s",
"select blobtestfield from test_table",
"where table_index = ? ");

EXEC SQL prepare demoid from :demoquery;

printf("SQLSTATE after PREAPARE is %s\n", SQLSTATE);

EXEC SQL declare democursor cursor for demoid;

EXEC SQL allocate descriptor 'demodesc';

strcpy( queryvalue, "tst7"); /*This row has a the blob field data as not null */
desc_count = 1;

if(desc_count > MAX_IDESC)
{
EXEC SQL deallocate descriptor 'demodesc';
EXEC SQL allocate descriptor 'demodesc' with max :desc_count;
}


printf("SQLSTATE after reallocate is %s\n", SQLSTATE);

/* number of parameters to be held in descriptor is 1 */
EXEC SQL set descriptor 'demodesc' COUNT = :desc_count;

/* Put the value of the parameter into the descriptor */
i = SQLCHAR;
EXEC SQL set descriptor 'demodesc' VALUE 1
TYPE = :i, LENGTH = 16, DATA = :queryvalue;

/* Associate the cursor with the parameter value */
EXEC SQL open democursor using sql descriptor 'demodesc';


/*Reuse the descriptor to determine the contents of the Select-list*/
EXEC SQL describe demoid using sql descriptor 'demodesc' ;
printf("SQLCODE:: DESCRIBE [%d] \n", SQLCODE);

EXEC SQL get descriptor 'demodesc' :desc_count = COUNT;

printf("There are %d returned columns:\n", desc_count);
/* Print out what DESCRIBE returns */
for (i = 1; i <= desc_count; i++)
prsysdesc(i);
printf("\n\n");




for (;;)
{
EXEC SQL fetch democursor using sql descriptor 'demodesc' ;
[ HERE IS WHERE IT FAILS WITH -450 Error ]

printf("SQLCODE:: FETCH [%d] \n", SQLCODE);
printf("Fetch done \n");

if (strncmp(SQLSTATE, "00", 2) != 0)
break;


/* Print out the returned values */
for (i = 1; i <= desc_count; i++)
{

EXEC SQL GET DESCRIPTOR 'demodesc' VALUE :i :blob_descr = DATA;

/* EXEC SQL get descriptor 'demodesc' VALUE :i
:ind = INDICATOR, :blob_descr = DATA; */
printf("Column: %s\tValue: %s\n", colname, result);
}
printf("\n");
} /* End of outer for loop */

if (strncmp(SQLSTATE, "02", 2) != 0)
printf("SQLSTATE after fetch is %s\n", SQLSTATE);

EXEC SQL close democursor;

/* free resources for prepared statement and cursor */
EXEC SQL free demoid;
EXEC SQL free democursor;

/* free system-descriptor area */
EXEC SQL deallocate descriptor 'demodesc';

-----------------

I also tried the demo program dyn_sql.ec, making some mod. to suit my need. It fails with the same error ?
Can you please look at it and help me ?

Thanks a ton.

Messages In This Thread

• Problem with BLOB: ESQL
  DBLRN DBLRN -- Sunday, 19 October 2003, at 5:40 a.m.
  • Re: Problem with BLOB: ESQL
    Jonathan Leffler -- Tuesday, 21 October 2003, at 8:20 p.m.

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