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anything similair to SQL Distinct in DBisam |
Sat, May 16 2009 8:43 PM | Permanent Link |
"Rita" | Hi is there anything similair to the sql distinct directive in DBisam
tables. I dont want to use sql but I would like to only show one instance of a name like in a names table I only need one 'Young' even if there are 20 or more. I cant make it a unique index because of data loss. Rita |
Sun, May 17 2009 3:54 AM | Permanent Link |
Roy Lambert NLH Associates Team Elevate | Rita
You could probably cobble something together using the OnFilter event, or using a mixture of sql and tables but ASAIK there's nothing you can use directly. Roy Lambert [Team Elevate] |
Sun, May 17 2009 12:05 PM | Permanent Link |
"Rita" | Thanks Roy I found this and will check it out 1st lazy bitch
http://www.grebarsys.com/ SFD sounds good but is it I will soon find out. Rita |
Sun, May 17 2009 12:20 PM | Permanent Link |
"Rita" | "Roy Lambert" <roy.lambert@skynet.co.uk> wrote in message news:756FE26C-F65C-4C3A-AFAE-AE1DF1A75211@news.elevatesoft.com... I love it when something goes right I dl'd the demo was pleasently suprised to see a DBisam demo but thats not all it was an IW demo toboot. My lucky day its also half price yabbadabbadoo. Rita |
Mon, May 18 2009 3:47 AM | Permanent Link |
Roy Lambert NLH Associates Team Elevate | Rita
If all you wanted were the distinct values you'd probably be better off using SQL: SELECT DISTINCT Surname FROM Table That way you're assured of compatibility as DBISAM gets upgraded or you switch to a different database (eg ElevateDB) Roy Lambert [Team Elevate] |
Mon, May 18 2009 5:40 AM | Permanent Link |
"Rita" | "Roy Lambert" <roy.lambert@skynet.co.uk> wrote in message news:4B1D4392-2C5F-468F-9E59-E727BAAE1A93@news.elevatesoft.com... > > If all you wanted were the distinct values you'd probably be better off > using SQL: > Sorry Roy you have gone full circle on me there. Bad SQL naughty SQL > SELECT DISTINCT Surname FROM Table > I know how the SQL distinct works I want to avoid it as a 1gb of records is slowwwwwwwww SuperFastDistinct seemed a good idea see the elevate.public.thirdparty dated 25/04/2006 now I'am not sure. "A quote by GregF I don't understand why I would want to spend so much money on a product that a simple and coding solution can achieve, I mean geez in effect all you are doing is positioning on the first key and then seeking the next value and the fact it needs hierarchical indexes means the product is of no use to me unless I actually have an index on the fields++ required" Barry the guy behind it has not even updated the site it shows a discount from 2006 worded as June 06 sorta suckered me so no dough for him. All I have to do now is figure ouy how to do it from what GregF says. Rita |
Mon, May 18 2009 7:37 AM | Permanent Link |
Roy Lambert NLH Associates Team Elevate | Rita
DBISAM 4.25 on a Dell Vostro 1700 (2.5Ghz duo) select distinct _whofrom from mandn 4.5 secs returning 11867 records from 262500 records (.dat 114Mg, .blb 4Gb .idx 253Mb) Roy Lambert |
Mon, May 18 2009 8:57 AM | Permanent Link |
"Rita" | "Roy Lambert" <roy.lambert@skynet.co.uk> wrote in message news:54B62C8F-C3A6-44A6-BFE2-F3214D384219@news.elevatesoft.com... > select distinct _whofrom from mandn > > 4.5 secs returning 11867 records from 262500 records (.dat 114Mg, .blb 4Gb > .idx 253Mb) > So slowwwwwwwwwwwwwwww I guess i cant read 11867 records so why worry about the 4.4 secs extra. CS read is not a problem but what about writes and 50+ users its ok bench testing one but in a real data mine the miners hate SQL lags for what should be simple code. |
Mon, May 18 2009 9:30 AM | Permanent Link |
Sean | Rita,
Index the table by the key you are looking for. Start at the first record & get your first distinct value. Do what you want with it. Change the last character in the distinct value to the next ordinal value. For example, 'Jones' would become 'Jonet'. Do a find nearest on this value to get the next distinct key value. Repeat until no more are found. Probably not necessary for text data, but you could be safe and check for a string ending in a character 127 or 255 and in that case append a CHR(1) instead of changing the last character. Sean Rita wrote: > "Roy Lambert" <roy.lambert@skynet.co.uk> wrote in message > news:4B1D4392-2C5F-468F-9E59-E727BAAE1A93@news.elevatesoft.com... >> If all you wanted were the distinct values you'd probably be better off >> using SQL: >> > > Sorry Roy you have gone full circle on me there. > Bad SQL naughty SQL > >> SELECT DISTINCT Surname FROM Table >> > > I know how the SQL distinct works I want to avoid it as > a 1gb of records is slowwwwwwwww > > SuperFastDistinct seemed a good idea see the elevate.public.thirdparty > dated 25/04/2006 now I'am not sure. > > "A quote by GregF > I don't understand why I would want to spend so much money on a product > that a simple and coding solution can achieve, I mean geez in effect > all you are doing is positioning on the first key and then seeking the next > value > and the fact it needs hierarchical indexes means the product is of no use to > me unless I actually have an index on the fields++ required" > > Barry the guy behind it has not even updated the site it shows a discount > from 2006 worded as June 06 sorta suckered me so no dough for him. > All I have to do now is figure ouy how to do it from what GregF says. > Rita > > > > |
Mon, May 18 2009 10:07 AM | Permanent Link |
Roy Lambert NLH Associates Team Elevate | Rita
OK so what is the actual scenario. You want reads & writes over the internet? What size database in records, how many unique records do you expect to find etc? Roy Lambert |
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