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shapper
Constraint Violating Yak Guru
450 Posts |
 Posted - 2009-03-11 : 11:30:04
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| Hello,I am creating a internal URL alias on my application similar to TinyUrl: http://tinyurl.com/a21gsI was thinking in creating a table as follows:AliasIdAliasUrlSourceUrlFor example:http://www.mywebsite.com/document/show/ade59599-8686-49ab-b64d-35be3957e6aa would become: http://mywebsite.com/a1I believe in most applications I will only need a 2 characters length:26 letters + 10 digits = 2 ^ 36 combinations = 68 719 476 736Or maybe I could even change it to:AliasKey, SourceUrlSince AliasKey is always unique it can be used as PK and then I just add the basic url: http://mywebsite.com/ + AliasKey1. Is this possible?2. How can I generate a 2 character string using 2 of the 26 letters + 10 digits and be sure that does not exist in the table yet?Thanks,Miguel |
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SwePeso
Patron Saint of Lost Yaks
30421 Posts |
Posted - 2009-03-11 : 11:36:28
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Learn your math.26 + 10 combinations (36 combinations) for two positions are 36 * 36 total combinations which is 1296 combinations, not 68,719,476,736.What you have thought of, is to have an 2-combination switch for 36 positions. 2^36 is 68,719,476,736
E 12°55'05.63"N 56°04'39.26" |
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shapper
Constraint Violating Yak Guru
450 Posts |
Posted - 2009-03-11 : 12:01:18
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| Obviously ... I was calculating nAp and instead of making n^p I made p^n ...That was a mistake when writing fast my post ... Shame ...I am a Math College teacher ... lolSo I will increase the length and may drop a few more characters there ...Anyway, math is not really the problem.The problem is:- How to generate a random key and be sure that it is unique. Should this be made on SQL or on C# code?- And should I use the first or the second approach for the table?Forgive my mistake :-)Thank You,Miguel |
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shapper
Constraint Violating Yak Guru
450 Posts |
Posted - 2009-03-11 : 14:54:39
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| Should I use the table:AliasId (Guid - PK), ResourceUrl (nvarchar), AliasKey (nvarchar) Where AliasKey must be 4 characters length and unique.OR:AliasKey (nvarchar - PK), ResourceUrl (nvarchar) Where AliasKey must be 4 characters length and unique.Which approach should I use?And how can assure that AliasKey is unique?Thanks,MiguelThanks,Miguek |
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