UPDATING an IMAGE column in Sybase with PREPARED statement fails - sap-ase

Question

This is with ASE 15.7 and ESQL/C. Updating a row in a CURSOR with a prepared statement:
EXEC SQL BEGIN DECLARE SECTION;
CS_IMAGE image[512];
EXEC SQL END DECLARE SECTION;
strcpy(image, "foo");
EXEC SQL PREPARE updt FROM "UPDATE image_test SET nettodaten = ? WHERE CURRENT OF hc_image_test";
EXEC SQL EXECUTE updt USING :image;
fails with the message from ASE:
** SQLCODE=(-201)
** ASE Error
** Procedure *sq1625128094_1900377684ss* expects parameter
Invalid pointer param number 4, pointer value 0x(nil)
, which was not supplied.
What could be the reason for this?
Update 1
I modified the ESQL/C code a bit so it looks like this:
strcpy(anweisung, "UPDATE image_test SET katkey = ?, nettodaten = ? WHERE CURRENT OF hc_image_test");
EXEC SQL PREPARE updt FROM :anweisung;
EXEC SQL EXECUTE updt USING :key, :blobfld;
EXEC SQL CLOSE hc_image_test;
The error remains the same as above. But a look into the produced C-code by CPRE shows an interesting detail:
/*
** SQL STATEMENT: 17
** EXEC SQL EXECUTE updt USING :key, :blobfld;
*/
{
_SQL_CT_HANDLES * _sql;
_sqlinitctx(&_sql, CS_CURRENT_VERSION, CS_TRUE, &sqlca, (long
*)NULL, (CS_CHAR *)NULL);
if (_sql != (_SQL_CT_HANDLES *) NULL)
{
_sql->stmtData.persistent = CS_FALSE;
_sql->stmttype = SQL_EXECUTE;
_sql->connName.lnlen = CS_UNUSED;
_sql->stmtName.fnlen = 4;
strcpy(_sql->stmtName.first_name, "updt");
if ((_sql->retcode = _sqlprolog(_sql)) == CS_SUCCEED)
{
_sql->retcode = ct_dynamic(_sql->conn.command,
CS_EXECUTE, "updt", 4, NULL, CS_UNUSED);
if (_sql->retcode == CS_SUCCEED)
{
_sql->dfmtCS_INT_TYPE.count = 0;
_sql->dfmtCS_INT_TYPE.status = CS_INPUTVALUE;
_sql->retcode = ct_param(_sql->conn.command,
&_sql->dfmtCS_INT_TYPE, &key, (CS_INT)
CS_UNUSED, (CS_SMALLINT) 0);
_sql->dfmtCS_INT_TYPE.status = 0;
}
_sql->retcode = ct_send(_sql->conn.command);
_sql->hastate = (_sql->retcode == CS_RET_HAFAILOVER);
_sql->retcode = _sqlResults(_sql);
_sql->retcode = _sqlepilog(_sql);
}
if (sqlca.sqlcode < 0)
{
error_handler();
}
As one can see above, a pointer to the host variable CS_INT :key is placed with a call to ct_param() into the internal structures, but not any reference to the host variable CS_IMAGE :blobfld. And that's why ASE is complaining with a missing param value because it sees two question marks ? in the prepared UPDATE statement. This looks to me somehow as a bug in the CPRE compiler and not in ASE itself.

Answer 1

I have contacted through our maintenance contract the company SAP (the issue number there is 390674 / 2018) and some engineer is looking into this CPRE issue...
For the moment, I'm adding to the C-code produce by CPRE, short before the ct_send() call, the following lines of code to add the missing reference to the IMAGE column:
/* additional code for host var :blobfld */
if (_sql->retcode == CS_SUCCEED)
{
_sql->dfmtCS_IMAGE_TYPE.count = 0;
_sql->dfmtCS_IMAGE_TYPE.maxlength = (CS_INT) 65535;
_sql->dfmtCS_IMAGE_TYPE.format = CS_FMT_UNUSED;
_sql->dfmtCS_IMAGE_TYPE.status = CS_INPUTVALUE;
_sql->retcode = ct_param(_sql->conn.command,
&_sql->dfmtCS_IMAGE_TYPE, blobfld, (CS_INT) ImageLengthField,
(CS_SMALLINT) 0);
_sql->dfmtCS_IMAGE_TYPE.status = 0;
}
/* end of additional code for host var :blobfld */
_sql->retcode = ct_send(_sql->conn.command);
...
And all works fine.