Re: [Firebird-odbc-devel] selecting from Oracle 11g to firebird

[Hauser, K. <Kar...@ib...>]

I've tried to create the same scenario with a connection from oracle to mysql. By applying the statement:
------------
DECLARE
    l_nNR NUMBER := 1;
    l_strPuffer VARCHAR2(2000);
begin
    SELECT "first_name" INTO l_strPuffer
	FROM EMPLOYEE@myodbc
	WHERE "employee_id" = l_nNR;
end; 
----------
which forces the ODBC-Driver (or Oracle.. I don't know) to use bindings I got the following trace-part:
----------
dg4odbcMYODBC ( 12ac-f20	EXIT  SQLPrepare  with return code 0 (SQL_SUCCESS)
		HSTMT               01B51960
		UCHAR *             0x01E169F4 [      66] "SELECT A1.`first_name` FROM `EMPLOYEE` A1 WHERE A1.`employee_id`=?"
		SDWORD                    66

dg4odbcMYODBC ( 12ac-f20	ENTER SQLNumResultCols 
		HSTMT               01B51960
		SWORD *             0x01E002E8

dg4odbcMYODBC ( 12ac-f20	EXIT  SQLNumResultCols  with return code 0 (SQL_SUCCESS)
		HSTMT               01B51960
		SWORD *             0x01E002E8 (1)

dg4odbcMYODBC ( 12ac-f20	ENTER SQLBindParameter 
		HSTMT               01B51960
		UWORD                        1 
		SWORD                        1 <SQL_PARAM_INPUT>
		SWORD                        1 <SQL_C_CHAR>
		SWORD                        3 <SQL_DECIMAL>
		SQLULEN                    1
		SWORD                        0 
		PTR                0x01E16830
		SQLLEN                    65
		SQLLEN *            0x01E0F2E8
----------

You see, that oracle here also detects the col-type SQL_C_CHAR, whereas the original type of the column is numeric. The statement delivers the correct solution..

I've tried several things with the sources of the ODBC Driver (static replacing SQL_C_CHAR with SQL_C_DOUBLE as a simple test-> not working.. firebird says: no data found). Is there any documentation over the code of the ODBC Driver? I would know where Oracle jumps into the code..
SQLColAttribute? I found that other functions like this are traced, so I think that Oracle use another function.

-----Ursprüngliche Nachricht-----
Von: Alexander Potapchenko [mailto:ale...@re...] 
Gesendet: Donnerstag, 15. Januar 2009 01:12
An: fir...@li...
Betreff: Re: [Firebird-odbc-devel] selecting from Oracle 11g to firebird

Nikolay Samofatov wrote:
> Alexander,
>
> Oracle is not quite easy when it comes to numeric data types. Native 
> numeric in Oracle has 38 decimal digits, and as such can not always be 
> represented as SQL_INTEGER.
> Can you take an Oracle instance, and see what is going on when using 
> Firebird ODBC driver in the way described? This way we may let the users 
> from bank's IT department use our Firebird data warehousing databases 
> from their Oracle environment.
>   
Yes,  SQL_DOUBLE is a correctly data type in a general case for numeric. 
The main question is how Oracle detects parameters type for ODBC 
functions such as SQLBindParameter, SQLBindCol...
I think it must call SQLColAttribute for this. I did not try to use 
Firebird ODBC driver in Oracle as yet.

Alexander

-- 
Alexander Potapchenko
Senior developer

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