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World: r3wp

[SQLite] C library embeddable DB .

Graham
20-Mar-2006
[243x2]
what do the unix people use?
also, this doesn't handle date stamps with time/seconds.
Ashley
21-Mar-2006
[245]
gregorian values
 ... what's the format mask for that?
Graham
21-Mar-2006
[246x2]
this is now in unix timestamp 1142917662
oops, I think I meant Julian day numbers.
Pekr
21-Mar-2006
[248x2]
In Dbase, the date was stored in db in YYYYMMDD, so I vote for the 
date storage change too ... really helps sorting ...
Ashley - the question is, if there should be any delimiter in DB 
:-) You can write simple copy/part at .... if you want .... and load 
will load it into rebol format anyway, no?
Graham
21-Mar-2006
[250]
If they are stored as numbers, then just as easy to sort!
sqlab
21-Mar-2006
[251]
YYYYMMDD is the short form of the iso date, 
otherwise it should be YYYY-MM-DD, if I remember.
Pekr
21-Mar-2006
[252]
hmm, DBase tools have it like I said - YYYYMMDD, and it is question 
of date mask (which can be set upon locale, which rebol does not 
support :-), if you use dot, slash, whatever as a separator ...
Graham
21-Mar-2006
[253]
what about time??
Pekr
21-Mar-2006
[254]
iirc dbase does not support time datatype ...
Graham
21-Mar-2006
[255]
I meant I'd like to see a full timestamp datatype support.
sqlab
21-Mar-2006
[256x2]
it's also covered by ISO 8601
YYYY-MM-DD hh:mm:ss
or compact 
YYYYMMDDhhmmss
 I use mostly the compact form in my scripts.
If it's not for human communication, the space between date und time 
is a T
so now /precise is 2006-03-21T11:06:48.232+01
Pekr
21-Mar-2006
[258]
but it is easy to convert to - replace time-value "T" " " " :-)
sqlab
21-Mar-2006
[259]
It is easier for the console parser
JaimeVargas
21-Mar-2006
[260]
In unix the time is expressed in seconds and microseconds since midnight 
(0 hour), January 1, 1970.  The resolution of the system clock is 
hardware dependent, and the time may be updated continuously or in 
``ticks.'' 

The following structures are defined in <sys/time.h> as:

struct timeval {
        long    tv_sec;         /* seconds since Jan. 1, 1970 */
        long    tv_usec;        /* and microseconds */
};

struct timezone {
        int     tz_minuteswest; /* of Greenwich */

        int     tz_dsttime;     /* type of dst correction to apply */
};


The timezone structure indicates the local time zone (measured in 
minutes of time westward from Greenwich), and a flag that, if nonzero, 
indicates that Daylight Saving time applies locally during the appropriate 
part of the year.
Sunanda
21-Mar-2006
[261]
Worth noting that they are UNIX seconds not UTC seconds.....UNIX 
time does not recognise leap seconds, so it's now seven (I think) 
seconds adrift.
http://en.wikipedia.org/wiki/Unix_time
JaimeVargas
21-Mar-2006
[262]
Indeed, However I think the timezone files can be used to do the 
adjustment if desired, and this may happen in the future.
Ashley
21-Mar-2006
[263]
Pekr, "the question is, if there should be any delimiter in DB". 
There has to be, otherwise LOAD will treat "20060101" as an integer 
not a date. Remember that SQLite has no concept of "column types" 
so the MOLDed values themselves have to carry / represent the REBOL 
type when LOADed. What we are trying to do with date is to use an 
alternate representation that REBOL will still recognize as a date 
but that also happens to sort correctly; YYYY-MM-DD achieves both 
those objectives, it's just a cosmetic question as to what delimiter 
"looks" better if someone looks at the raw data (prior to being LOADed 
into REBOL values) or uses the format directly in their statements 
(e.g. "select * from t where date = '2006-01-01'").


Graham, "If they are stored as numbers, then just as easy to sort!" 
Yes, but as per above we lose the fact that they are dates. If they 
are stored as integer then we'll get them back as integers.


Graham, "what about time?" REBOL time values (in HH:MM:SS format) 
are already supported, and nothing prevents you from using now / 
now/precise except that these values will not be sorted correctly 
[with an "order by" clause that is].
Graham
21-Mar-2006
[264]
is datestamp also going to store the timezone ?
Ashley
21-Mar-2006
[265x2]
It simply MOLDs whatever now / now/precise returns. There is no "datestamp" 
type in REBOL per se (as date! covers both the short and long forms).
Mind you, I can always extend the date handling logic (as posted 
previously) to check to see whether the date has a time component; 
something like:

	if val/time [...]


Should we be checking for a zone component as well? The shortest 
possible timestamp that REBOL will recognize is:

	type? load "2006-01-01/13:30"

But that excludfes both seconds and zone.
Graham
21-Mar-2006
[267x2]
I was thinking that if you wanted a log, you might need timestamps 
...
My synapse chat program also stores timestamps and needs the timezone 
so that other users not in NZ can translate the timestamp to local 
time.
Robert
22-Mar-2006
[269]
Didn't played around with SQLite yet. But I expect that a result 
set is returned. Isn't it than possible to use Rebol to sort the 
result set? It can handle all datatypes.
Ashley
22-Mar-2006
[270]
Agreed. It's just that almost every datatype apart from date (pair! 
is also problematic) happens to sort correctly under SQLite as is; 
and changing date's TEXT representation so that it sorts correctly 
within SQLite is fairly easy. I'd rather write:

	result: SQL "select id,date from t order by date"


than:

	result: sort/skip SQL "select id,date from t"  2

as it's both easier to maintain and more efficient.
Robert
23-Mar-2006
[271x2]
Ok, that makes sense.
Is the linking between SQLite and RebGUI already implemented? In 
that if I get back a result set, that I can use it directly to fill 
a list or drop-down list? Or load a result set into a form?
Ashley
23-Mar-2006
[273]
Yes, just use CONNECT/flat and the driver will return all values 
in a single block which RebGUI can use directly in lists and tables 
(no conversion required).
Robert
24-Mar-2006
[274x2]
Great! :-)
Next question, before I start using SQLit and RebGUI now. How do 
you handle the identification of table rows? Do you display the record 
ID or can the record ID be a hidden entry?
Ashley
24-Mar-2006
[276]
I display the record ID (which maps to a unique entity ID such as 
patient#, order#, ect) and which the end-user is usually interested 
in seeing anyway (as it ties in to their other systems). If you want 
to hide the column in RebGUI then just give it a width specification 
of 0 and ensure it is not the last column.
Ingo
25-Mar-2006
[277x2]
... or you could explicitly name all columns you want to display 
play in your select statement

	select * from persons; 

becomes

	select firstname, lastname from person;
the concatenation operator || does not work. If I do:

	SELECT firstname || lastname AS name from person;

I still get blocks of 2 values, not one.
Ashley
25-Mar-2006
[279x3]
Replace the column-text block in the SQL function with:

	[(
		either direct [
			[*column-text (sid) idx]
		][
			[
				s: v: *column-text (sid) idx
				while [s: find s {""}] [change/part s "" 2]
				load v
			]
		]
	)]

I've added this to the next build.
0.1.8 available at: http://www.dobeash.com/SQLite/sqlite.r


Two main fixes are date bind value handling and concatenated string 
handling (both of which were posted previously as code snippets).
0.1.9 posted with improved concatenation handling logic. In addition 
to handling strings you can now also do:

	SQL "select name||100 from customers"

and

	SQL {select id||'"-'"||name from customers}


Most REBOL types are supported (in concatenation type operations) 
although blocks may cause problems.
Ingo
26-Mar-2006
[282x2]
thanks Ashley. I already found out, that it works when using direct. 
Now going to check the new versions.
BTW, is there a speed gain when using direct? I only save strings 
atm, anyway.
Ashley
26-Mar-2006
[284]
Direct: definite speed gain as MOLD / LOAD is bypassed for each and 
every value bound / retrieved. /flat (if your data structure can 
use it) is also faster and uses less memory - although the gain is 
more noticeable with larger numbers of rows.
Ingo
30-Mar-2006
[285]
Is it possible to check, wether a database is already connected?
Ashley
30-Mar-2006
[286]
DATABASE function?
Thør
2-Apr-2006
[287]
initial sync...
Ingo
3-Apr-2006
[288x2]
Right, that's it! Don't know why I haven't seen it ;-)
Although, if you are not connected to any database, it raises an 
error just like any other function. 

I think it would be helpful to have a function to just check, maybe 
like ...


either none? database [ ... you hev to connect ....][ ... check whether 
the right database is corrected ...]
Robert
3-Apr-2006
[290x2]
Value Binding: Is something like this possible as well?

	SQL ["select * from ? where col_1 = ?" mytable 1]
IMO it would be very handy, because those statements can be prepared 
and assigned to rebol words, for simple access in an application. 
It the SQL statement changes, I only have to do it at one place.
Ashley
3-Apr-2006
[292]
Not sure, havn't tried yet.