FreeTDS Development Group

[Brian Bruns <camber AT umcc.ais.org>]

I don't know if this will help or not, but return results usually have a
size for variable data or the data alone for fixed length data, thus 0
could indicate a length of 0 or null. 

Oh and can you send in some of the ODBC code in? I have no experience w/
ODBC and thus have no code to base the odbc cli on whn it's time to write 
it.

I don't have time to look at the dump now, but I'll try to take some time
tonight.  BTW, I have some of the code for handling compute columns in my
version, I'll try to move it up soon.


Brian

On Mon, 14 Sep 1998, Craig Spannring wrote:

> 
> I'm trying to figure out how to execute a prepared statement in TDS
> 4.2.  I wrote a little C program using ODBC to see what kinds of
> packets are sent by the Microsoft ODBC driver.  My prepared statement
> was
>    select * from many_types where (myint=? and mynullableint=?) or myint=?"
> I have bound the first and third parameters with a value of 0x000003ff, the
> second parameter to null.
> 
> In packet 16 (the invocation of the procedure) I can see that the
> first and third parameters are 
>    0x38 0xff 0x03 0x00 x000
> I assume the 0x38 corresponds to SYBINT4.  The 0xff 0x03 0x00 0x00 is 
> obviously the value of the parameter.
> 
> The part I'm confused about is the second parameter.  It was bound to
> SQL_NULL and looks like 
>    0x00 0x00 0x26 0x04 0x00 0x00 0x00
> The first byte (which normally indicates the type of data) is set to
> 0x00 which seems like a reasonable way of specifying NULL.  Does
> anyone have any guesses as to the next 6 bytes?
> 
> 
> 
> Here is the dump of the network traffic.  I've formatted it so that
> the header is parsed out and doesn't show up in the hex dump.
> 
>   Packet 14,  10:02:07.840524
>   Source:        client.internetcds.com
>   Destination:   server.internetcds.com
>   type?: 1 (QUERY)
>   status?: 1
>   length: 147
>   channel?: 0
>   packet?: 1
>   window?: 0
>   0000  01 01 00 93 00 00 01 00 63 72 65 61 74 65 20 70   |........create p|
>   0010  72 6f 63 20 23 6f 64 62 63 23 70 6c 61 74 72 65   |roc #odbc#platre|
>   0020  39 39 38 37 62 35 30 28 40 50 31 20 69 6e 74 2c   |9987b50(@P1 int,|
>   0030  40 50 32 20 69 6e 74 2c 40 50 33 20 69 6e 74 29   |@P2 int,@P3 int)|
>   0040  20 61 73 20 73 65 6c 65 63 74 20 2a 20 66 72 6f   | as select * fro|
>   0050  6d 20 6d 61 6e 79 5f 74 79 70 65 73 20 77 68 65   |m many_types whe|
>   0060  72 65 20 28 6d 79 69 6e 74 3d 40 50 31 20 20 20   |re (myint=@P1   |
>   0070  61 6e 64 20 6d 79 6e 75 6c 6c 61 62 6c 65 69 6e   |and mynullablein|
>   0080  74 3d 40 50 32 29 20 6f 72 20 6d 79 69 6e 74 3d   |t=@P2) or myint=|
>   0090  40 50 33                                          |@P3|
>   
>   Packet 15,  10:02:07.868152
>   Source:        server.internetcds.com
>   Destination:   client.internetcds.com
>   type?: 4 (REPLY)
>   status?: 1
>   length: 17
>   channel?: 0
>   packet?: 0
>   window?: 0
>   0000  04 01 00 11 00 00 00 00 fd 00 00 fd 00 00 00 00   |................|
>   0010  00                                                |.|
>   
>   Packet 16,  10:02:07.868951
>   Source:        client.internetcds.com
>   Destination:   server.internetcds.com
>   type?: 3 (PROC)
>   status?: 1
>   length: 49
>   channel?: 0
>   packet?: 1
>   window?: 0
>   0000  03 01 00 31 00 00 01 00 13 23 6f 64 62 63 23 70   |...1.....#odbc#p|
>   0010  6c 61 74 72 65 39 39 38 37 62 35 30 00 00 00 00   |latre9987b50....|
>   0020  38 ff 03 00 00 00 00 26 04 00 00 00 38 ff 03 00   |8......&....8...|
>   0030  00                                                |.|
> 
>  
> -- 
> =======================================================================
>  Life is short.                  | Craig Spannring 
>       Ski hard, Bike fast.       | cts AT internetcds.com
>  --------------------------------+------------------------------------
>  Any sufficiently perverted technology is indistinguishable from Perl.
> =======================================================================
> 
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