[freetds] db-lib: support for new MS SQL 2008 data types - part 3

LacaK lacak at zoznam.sk
Thu Apr 17 01:26:14 EDT 2014


Frediano Ziglio  wrote / napísal(a):
> 2014-04-16 12:44 GMT+01:00 LacaK <lacak at zoznam.sk>:
>   
>> Hi again,
>> Now I am personally happy with patched db-lib in regards of support new DATE
>> - TIME data types.
>>     
>
> Great! Yesterday I discovered a problem with BCP adding some tests for
> these new types, still to fix.
>
>   

May be, I have never used bcp_* functions ;-)


>> But there are still missing some parts, which may be interesting to somebody
>> else.
>> I meant dbbind() family of API with corresponding *BIND constants and binary
>> structure used to store this types.
>>
>> How to handle binding of new date, time types ?
>>
>> - introduce new DBDATETIMEALLBIND (or DBDATETIME2BIND) constant in sybdb.h ?
>>     
>
> could work
>
>   
>> - introduce new DBDATETIMEALL struct (==TDS_DATETIMEALL struct) in sybdb.h
>> ?
>>     
>
> Mmm... well... could be or not. Microsoft for ODBC defined quite
> different structures (one more similar to DBDATEREC). TDS_DATETIMEALL
> is neither from TDS protocol neither intended to be presented to
> clients. It's a mix of TDS protocols, numeric, old dates (values are
> the same as dtdays).

>  On the other end I could understand that
> providing dbdata different from libTDS is far from easy.
>
>   
Exactlly!
It is main reason why I am still speaking about TDS_DATETIMEALL ;-)
And as I already wrote because of similarity of:
SQL Server       libTDS                          DB-Lib
------------------------------------------------------------
datetime        -> TDS_DATETIME   == DBDATETIME
smalldatetime ->TDS_DATETIME4 == DBDATETIME4

I will be happy also with SQL_TIMESTAMP_STRUCT (or other struct), to be 
public structure for these new date time data types, but IMO then this 
struct must be used also internaly by libTDS to store values in record 
buffer. Because if libTDS will continue use TDS_DATETIMEALL then it will 
significantly complicate things on db-lib level. (as there will be 
required conversion in many places)

>> - add support to copy_data_to_host_var() function in dblib.c ?
>>
>>     
>
> Ehmm... what do you mean?
>
>   
In db-lib is function copy_data_to_host_var() which is called when next 
record is fetched to store fetched column values to local program 
variables for bind columns.
If you look at this function there are performed type conversions very 
simlar to dbconvert().
So we must add there also cases for SYBMSDATE...SYBMSDATETIMEOFFSET 
(like we did for dbconvert())

>> If you give me direction I can prepare patch ...
>> (if it is good idea add support for BINDing ?)
>>     
>
> Not good, excellent! And much easier as you don't have to store a
> buffer but you can provide what do you want to the client.
>   
Yes

So only think we must agree on is : what "struct" we will use for new 
date time data types ?
If it will be TDS_DATETIMEALL then it makes things easy and compact.
If it must be something else then my proposal is use same struct in 
libTDS instead of TDS_DATETIMEALL.

Thanks
-Laco.



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