Re: [GENERAL] Some insight on the proper SQL would be appreciated
In article <4c0f4ba8.3040...@gmail.com>, Ognjen Blagojevic writes: > Plenty of solutions here: > http://www.xaprb.com/blog/2006/12/07/how-to-select-the-firstleastmax-row-per-group-in-sql/ This doesn't mention the incredibly powerful windowing functions of PostgreSQL >= 8.4.0: SELECT username, firstname, lastname, signedup FROM ( SELECT username, firstname, lastname, signedup, row_number() OVER (PARTITION BY username ORDER BY signedup) FROM mytbl ) dummy WHERE row_number <= 5 -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
Re: [GENERAL] Some insight on the proper SQL would be appreciated
On 8 June 2010 17:29, Aaron Burnett wrote: > > Greetings, > > I hope this is the proper list for this, but I am a loss on how to achieve > one particular set of results. > > I have a table which is a list of users who entered a contest. They can > enter as many times as they want, but only 5 will count. So some users have > one entry, some have as many as 15. > > How could I distill this down further to give me a list that shows each > entry per user up to five entries per user? In other words, I need a > separate line item for each entry from each user up to the maximum of 5 rows > per user. > > Table looks like this: > username | firstname | lastname | signedup > --+---+-+--- > - > ffc4bd0a-ccff-4203-a03c-4bd6b8c23a03 | Jean | Mathews | 2010-03-13 > ffc4bd0a-ccff-4203-a03c-4bd6b8c23a03 | Jean | Mathews | 2010-05-07 > ffc4bd0a-ccff-4203-a03c-4bd6b8c23a03 | Jean | Mathews | 2010-06-06 > ff8720d4-f808-4ee6-90e6-649872fdfa55 | Janis | Bunch | 2010-03-12 > ff48d89b-6afe-4ba0-8539-9683bec62c89 | Sandy | Yashnyk | 2010-04-25 > ff48d2a4-0637-4e46-9461-3dd0dc0d4d83 | Kendra | Elliott | 2010-05-09 > ff3a2a14-2575-44d5-b40b-3780f4d2506a | Kay | Maher | 2010-04-20 > fef7625b-d1e1-4c1a-bc82-d35a4a6db16d | Carolyn | Woodul | 2010-04-05 > fef21bbb-07a0-4c84-8708-4dc41b8b770b | Laurie | Montijo | 2010-04-03 > feee6473-af4d-4e70-b20c-a74ba08c000f | Geneva | Anderson | 2010-04-03 > feb690fc-0afb-4e87-b0d1-bdb2c4603fd1 | Judith | Astroff | 2010-06-05 > fea0f9a6-e89f-4dbd-b3fd-83efed27221f | Jennifer | Lavigne | 2010-02-09 > fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-03-20 > fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-03-27 > fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-03 > fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-10 > fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-17 > fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-25 > fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-05-01 > fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-05-08 > fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-05-16 > fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-05-22 > fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-05-30 > fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-06-06 > fe825a6d-6820-4282-b8e9-2e3cb9f660e8 | Susan | Stowe | 2010-03-12 > fe825a6d-6820-4282-b8e9-2e3cb9f660e8 | Susan | Stowe | 2010-03-15 > > But in John Smith's case where he has more than 5 entries, I would like > query results to limit him to just 5 entries to look like this: > > username | firstname | lastname | signedup > --+---+-+--- > - > ffc4bd0a-ccff-4203-a03c-4bd6b8c23a03 | Jean | Mathews | 2010-03-13 > ffc4bd0a-ccff-4203-a03c-4bd6b8c23a03 | Jean | Mathews | 2010-05-07 > ffc4bd0a-ccff-4203-a03c-4bd6b8c23a03 | Jean | Mathews | 2010-06-06 > ff8720d4-f808-4ee6-90e6-649872fdfa55 | Janis | Bunch | 2010-03-12 > ff48d89b-6afe-4ba0-8539-9683bec62c89 | Sandy | Yashnyk | 2010-04-25 > ff48d2a4-0637-4e46-9461-3dd0dc0d4d83 | Kendra | Elliott | 2010-05-09 > ff3a2a14-2575-44d5-b40b-3780f4d2506a | Kay | Maher | 2010-04-20 > fef7625b-d1e1-4c1a-bc82-d35a4a6db16d | Carolyn | Woodul | 2010-04-05 > fef21bbb-07a0-4c84-8708-4dc41b8b770b | Laurie | Montijo | 2010-04-03 > feee6473-af4d-4e70-b20c-a74ba08c000f | Geneva | Anderson | 2010-04-03 > feb690fc-0afb-4e87-b0d1-bdb2c4603fd1 | Judith | Astroff | 2010-06-05 > fea0f9a6-e89f-4dbd-b3fd-83efed27221f | Jennifer | Lavigne | 2010-02-09 > fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-03-20 > fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-03-27 > fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-03 > fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-10 > fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-17 > fe825a6d-6820-4282-b8e9-2e3cb9f660e8 | Susan | Stowe | 2010-03-12 > fe825a6d-6820-4282-b8e9-2e3cb9f660e8 | Susan | Stowe | 2010-03-15 > > The username is unique for each user. > > pg version 8.25 on RHEL > > Any help in this would be greatly appreciated. > > Thank you. > Bit crude, but if you have an id column, try: SELECT username, firstname, lastname, signedup FROM entries WHERE id IN (SELECT id FROM entries limitedentries WHERE limitedentries.username = entries.username ORDER BY
Re: [GENERAL] Some insight on the proper SQL would be appreciated
Plenty of solutions here: http://www.xaprb.com/blog/2006/12/07/how-to-select-the-firstleastmax-row-per-group-in-sql/ -Ognjen On 8.6.2010 18:29, Aaron Burnett wrote: Greetings, I hope this is the proper list for this, but I am a loss on how to achieve one particular set of results. I have a table which is a list of users who entered a contest. They can enter as many times as they want, but only 5 will count. So some users have one entry, some have as many as 15. How could I distill this down further to give me a list that shows each entry per user up to five entries per user? In other words, I need a separate line item for each entry from each user up to the maximum of 5 rows per user. Table looks like this: username | firstname | lastname | signedup --+---+-+--- - ffc4bd0a-ccff-4203-a03c-4bd6b8c23a03 | Jean | Mathews | 2010-03-13 ffc4bd0a-ccff-4203-a03c-4bd6b8c23a03 | Jean | Mathews | 2010-05-07 ffc4bd0a-ccff-4203-a03c-4bd6b8c23a03 | Jean | Mathews | 2010-06-06 ff8720d4-f808-4ee6-90e6-649872fdfa55 | Janis | Bunch | 2010-03-12 ff48d89b-6afe-4ba0-8539-9683bec62c89 | Sandy | Yashnyk | 2010-04-25 ff48d2a4-0637-4e46-9461-3dd0dc0d4d83 | Kendra| Elliott | 2010-05-09 ff3a2a14-2575-44d5-b40b-3780f4d2506a | Kay | Maher | 2010-04-20 fef7625b-d1e1-4c1a-bc82-d35a4a6db16d | Carolyn | Woodul | 2010-04-05 fef21bbb-07a0-4c84-8708-4dc41b8b770b | Laurie| Montijo | 2010-04-03 feee6473-af4d-4e70-b20c-a74ba08c000f | Geneva| Anderson| 2010-04-03 feb690fc-0afb-4e87-b0d1-bdb2c4603fd1 | Judith| Astroff | 2010-06-05 fea0f9a6-e89f-4dbd-b3fd-83efed27221f | Jennifer | Lavigne | 2010-02-09 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-03-20 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-03-27 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-03 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-10 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-17 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-25 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-05-01 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-05-08 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-05-16 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-05-22 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-05-30 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-06-06 fe825a6d-6820-4282-b8e9-2e3cb9f660e8 | Susan | Stowe | 2010-03-12 fe825a6d-6820-4282-b8e9-2e3cb9f660e8 | Susan | Stowe | 2010-03-15 But in John Smith's case where he has more than 5 entries, I would like query results to limit him to just 5 entries to look like this: username | firstname | lastname | signedup --+---+-+--- - ffc4bd0a-ccff-4203-a03c-4bd6b8c23a03 | Jean | Mathews | 2010-03-13 ffc4bd0a-ccff-4203-a03c-4bd6b8c23a03 | Jean | Mathews | 2010-05-07 ffc4bd0a-ccff-4203-a03c-4bd6b8c23a03 | Jean | Mathews | 2010-06-06 ff8720d4-f808-4ee6-90e6-649872fdfa55 | Janis | Bunch | 2010-03-12 ff48d89b-6afe-4ba0-8539-9683bec62c89 | Sandy | Yashnyk | 2010-04-25 ff48d2a4-0637-4e46-9461-3dd0dc0d4d83 | Kendra| Elliott | 2010-05-09 ff3a2a14-2575-44d5-b40b-3780f4d2506a | Kay | Maher | 2010-04-20 fef7625b-d1e1-4c1a-bc82-d35a4a6db16d | Carolyn | Woodul | 2010-04-05 fef21bbb-07a0-4c84-8708-4dc41b8b770b | Laurie| Montijo | 2010-04-03 feee6473-af4d-4e70-b20c-a74ba08c000f | Geneva| Anderson| 2010-04-03 feb690fc-0afb-4e87-b0d1-bdb2c4603fd1 | Judith| Astroff | 2010-06-05 fea0f9a6-e89f-4dbd-b3fd-83efed27221f | Jennifer | Lavigne | 2010-02-09 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-03-20 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-03-27 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-03 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-10 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-17 fe825a6d-6820-4282-b8e9-2e3cb9f660e8 | Susan | Stowe | 2010-03-12 fe825a6d-6820-4282-b8e9-2e3cb9f660e8 | Susan | Stowe | 2010-03-15 The username is unique for each user. pg version 8.25 on RHEL Any help in this would be greatly appreciated. Thank you. -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
Re: [GENERAL] Some insight on the proper SQL would be appreciated
Andy Colson wrote: >> thanks very much Andy. Very elegant. >> I do need to presere the users that have<5 entries though, so I think I can >> modify your function to do that as well. > Oh, duh! because nothing is less than 1900-01-01... my > date math sucks. It should probably return '2100-01-01' or > something. If you're using stored functions, you could (and should be- cause the whole table is probably read anyhow) also code a function that reads all entries, resets a counter at the start and whenever the user changes, increments it on every row and returns all rows where the counter is less than five. Tim -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
Re: [GENERAL] Some insight on the proper SQL would be appreciated
On 6/8/2010 2:08 PM, Aaron Burnett wrote: thanks very much Andy. Very elegant. I do need to presere the users that have<5 entries though, so I think I can modify your function to do that as well. Thanks again. Oh, duh! because nothing is less than 1900-01-01... my date math sucks. It should probably return '2100-01-01' or something. -Andy -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
Re: [GENERAL] Some insight on the proper SQL would be appreciated
On 6/8/2010 11:29 AM, Aaron Burnett wrote: Greetings, I hope this is the proper list for this, but I am a loss on how to achieve one particular set of results. I have a table which is a list of users who entered a contest. They can enter as many times as they want, but only 5 will count. So some users have one entry, some have as many as 15. How could I distill this down further to give me a list that shows each entry per user up to five entries per user? In other words, I need a separate line item for each entry from each user up to the maximum of 5 rows per user. Table looks like this: username | firstname | lastname | signedup --+---+-+--- - ffc4bd0a-ccff-4203-a03c-4bd6b8c23a03 | Jean | Mathews | 2010-03-13 ffc4bd0a-ccff-4203-a03c-4bd6b8c23a03 | Jean | Mathews | 2010-05-07 ffc4bd0a-ccff-4203-a03c-4bd6b8c23a03 | Jean | Mathews | 2010-06-06 ff8720d4-f808-4ee6-90e6-649872fdfa55 | Janis | Bunch | 2010-03-12 ff48d89b-6afe-4ba0-8539-9683bec62c89 | Sandy | Yashnyk | 2010-04-25 ff48d2a4-0637-4e46-9461-3dd0dc0d4d83 | Kendra| Elliott | 2010-05-09 ff3a2a14-2575-44d5-b40b-3780f4d2506a | Kay | Maher | 2010-04-20 fef7625b-d1e1-4c1a-bc82-d35a4a6db16d | Carolyn | Woodul | 2010-04-05 fef21bbb-07a0-4c84-8708-4dc41b8b770b | Laurie| Montijo | 2010-04-03 feee6473-af4d-4e70-b20c-a74ba08c000f | Geneva| Anderson| 2010-04-03 feb690fc-0afb-4e87-b0d1-bdb2c4603fd1 | Judith| Astroff | 2010-06-05 fea0f9a6-e89f-4dbd-b3fd-83efed27221f | Jennifer | Lavigne | 2010-02-09 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-03-20 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-03-27 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-03 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-10 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-17 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-25 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-05-01 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-05-08 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-05-16 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-05-22 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-05-30 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-06-06 fe825a6d-6820-4282-b8e9-2e3cb9f660e8 | Susan | Stowe | 2010-03-12 fe825a6d-6820-4282-b8e9-2e3cb9f660e8 | Susan | Stowe | 2010-03-15 But in John Smith's case where he has more than 5 entries, I would like query results to limit him to just 5 entries to look like this: username | firstname | lastname | signedup --+---+-+--- - ffc4bd0a-ccff-4203-a03c-4bd6b8c23a03 | Jean | Mathews | 2010-03-13 ffc4bd0a-ccff-4203-a03c-4bd6b8c23a03 | Jean | Mathews | 2010-05-07 ffc4bd0a-ccff-4203-a03c-4bd6b8c23a03 | Jean | Mathews | 2010-06-06 ff8720d4-f808-4ee6-90e6-649872fdfa55 | Janis | Bunch | 2010-03-12 ff48d89b-6afe-4ba0-8539-9683bec62c89 | Sandy | Yashnyk | 2010-04-25 ff48d2a4-0637-4e46-9461-3dd0dc0d4d83 | Kendra| Elliott | 2010-05-09 ff3a2a14-2575-44d5-b40b-3780f4d2506a | Kay | Maher | 2010-04-20 fef7625b-d1e1-4c1a-bc82-d35a4a6db16d | Carolyn | Woodul | 2010-04-05 fef21bbb-07a0-4c84-8708-4dc41b8b770b | Laurie| Montijo | 2010-04-03 feee6473-af4d-4e70-b20c-a74ba08c000f | Geneva| Anderson| 2010-04-03 feb690fc-0afb-4e87-b0d1-bdb2c4603fd1 | Judith| Astroff | 2010-06-05 fea0f9a6-e89f-4dbd-b3fd-83efed27221f | Jennifer | Lavigne | 2010-02-09 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-03-20 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-03-27 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-03 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-10 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-17 fe825a6d-6820-4282-b8e9-2e3cb9f660e8 | Susan | Stowe | 2010-03-12 fe825a6d-6820-4282-b8e9-2e3cb9f660e8 | Susan | Stowe | 2010-03-15 The username is unique for each user. pg version 8.25 on RHEL Any help in this would be greatly appreciated. Thank you. Ok, here we go. Add this function: CREATE OR REPLACE FUNCTION fifth(uid text) RETURNS timestamp without time zone LANGUAGE plpgsql IMMUTABLE AS $function$ declare result timestamp; begin select signedup into result from users where u
Re: [GENERAL] Some insight on the proper SQL would be appreciated
On 6/8/2010 11:29 AM, Aaron Burnett wrote: Greetings, I hope this is the proper list for this, but I am a loss on how to achieve one particular set of results. I have a table which is a list of users who entered a contest. They can enter as many times as they want, but only 5 will count. So some users have one entry, some have as many as 15. How could I distill this down further to give me a list that shows each entry per user up to five entries per user? In other words, I need a separate line item for each entry from each user up to the maximum of 5 rows per user. Table looks like this: username | firstname | lastname | signedup --+---+-+--- - ffc4bd0a-ccff-4203-a03c-4bd6b8c23a03 | Jean | Mathews | 2010-03-13 ffc4bd0a-ccff-4203-a03c-4bd6b8c23a03 | Jean | Mathews | 2010-05-07 ffc4bd0a-ccff-4203-a03c-4bd6b8c23a03 | Jean | Mathews | 2010-06-06 ff8720d4-f808-4ee6-90e6-649872fdfa55 | Janis | Bunch | 2010-03-12 ff48d89b-6afe-4ba0-8539-9683bec62c89 | Sandy | Yashnyk | 2010-04-25 ff48d2a4-0637-4e46-9461-3dd0dc0d4d83 | Kendra| Elliott | 2010-05-09 ff3a2a14-2575-44d5-b40b-3780f4d2506a | Kay | Maher | 2010-04-20 fef7625b-d1e1-4c1a-bc82-d35a4a6db16d | Carolyn | Woodul | 2010-04-05 fef21bbb-07a0-4c84-8708-4dc41b8b770b | Laurie| Montijo | 2010-04-03 feee6473-af4d-4e70-b20c-a74ba08c000f | Geneva| Anderson| 2010-04-03 feb690fc-0afb-4e87-b0d1-bdb2c4603fd1 | Judith| Astroff | 2010-06-05 fea0f9a6-e89f-4dbd-b3fd-83efed27221f | Jennifer | Lavigne | 2010-02-09 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-03-20 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-03-27 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-03 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-10 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-17 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-25 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-05-01 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-05-08 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-05-16 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-05-22 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-05-30 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-06-06 fe825a6d-6820-4282-b8e9-2e3cb9f660e8 | Susan | Stowe | 2010-03-12 fe825a6d-6820-4282-b8e9-2e3cb9f660e8 | Susan | Stowe | 2010-03-15 But in John Smith's case where he has more than 5 entries, I would like query results to limit him to just 5 entries to look like this: username | firstname | lastname | signedup --+---+-+--- - ffc4bd0a-ccff-4203-a03c-4bd6b8c23a03 | Jean | Mathews | 2010-03-13 ffc4bd0a-ccff-4203-a03c-4bd6b8c23a03 | Jean | Mathews | 2010-05-07 ffc4bd0a-ccff-4203-a03c-4bd6b8c23a03 | Jean | Mathews | 2010-06-06 ff8720d4-f808-4ee6-90e6-649872fdfa55 | Janis | Bunch | 2010-03-12 ff48d89b-6afe-4ba0-8539-9683bec62c89 | Sandy | Yashnyk | 2010-04-25 ff48d2a4-0637-4e46-9461-3dd0dc0d4d83 | Kendra| Elliott | 2010-05-09 ff3a2a14-2575-44d5-b40b-3780f4d2506a | Kay | Maher | 2010-04-20 fef7625b-d1e1-4c1a-bc82-d35a4a6db16d | Carolyn | Woodul | 2010-04-05 fef21bbb-07a0-4c84-8708-4dc41b8b770b | Laurie| Montijo | 2010-04-03 feee6473-af4d-4e70-b20c-a74ba08c000f | Geneva| Anderson| 2010-04-03 feb690fc-0afb-4e87-b0d1-bdb2c4603fd1 | Judith| Astroff | 2010-06-05 fea0f9a6-e89f-4dbd-b3fd-83efed27221f | Jennifer | Lavigne | 2010-02-09 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-03-20 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-03-27 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-03 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-10 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-17 fe825a6d-6820-4282-b8e9-2e3cb9f660e8 | Susan | Stowe | 2010-03-12 fe825a6d-6820-4282-b8e9-2e3cb9f660e8 | Susan | Stowe | 2010-03-15 The username is unique for each user. pg version 8.25 on RHEL Any help in this would be greatly appreciated. Thank you. Ok, here we go. Add this function: CREATE OR REPLACE FUNCTION fifth(uid text) RETURNS timestamp without time zone LANGUAGE plpgsql IMMUTABLE AS $function$ declare result timestamp; begin select signedup into result from users where usename = uid order by signedup limit 1 offset 4;
Re: [GENERAL] Some insight on the proper SQL would be appreciated
On 6/8/2010 11:29 AM, Aaron Burnett wrote: Greetings, I hope this is the proper list for this, but I am a loss on how to achieve one particular set of results. I have a table which is a list of users who entered a contest. They can enter as many times as they want, but only 5 will count. So some users have one entry, some have as many as 15. is it possible to add a new column: "isValid integer" (or something like it, to signify which one's can and cannot be selected) I was thinking of doing it in two steps, an update to set isValid, then a select with just "isValid = 1". Not sure how hard the update would be though. Oh, wait, I'll bet a window function would be helpful... but you are on 8.2 so I dont think you have them. I can think of a stored proc that might work, that ok? Oh, another thought.. if we order it by username, signedup, and then did something like: where ... signedup > (select the 5th signedup from users ... ) not 100% how to do the subselect though. I can see min(signedup) or max(signedup), but not sure how to get the 5th. Not real helpful, sorry, just some random thoughts -Andy -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
[GENERAL] Some insight on the proper SQL would be appreciated
Greetings, I hope this is the proper list for this, but I am a loss on how to achieve one particular set of results. I have a table which is a list of users who entered a contest. They can enter as many times as they want, but only 5 will count. So some users have one entry, some have as many as 15. How could I distill this down further to give me a list that shows each entry per user up to five entries per user? In other words, I need a separate line item for each entry from each user up to the maximum of 5 rows per user. Table looks like this: username | firstname | lastname | signedup --+---+-+--- - ffc4bd0a-ccff-4203-a03c-4bd6b8c23a03 | Jean | Mathews | 2010-03-13 ffc4bd0a-ccff-4203-a03c-4bd6b8c23a03 | Jean | Mathews | 2010-05-07 ffc4bd0a-ccff-4203-a03c-4bd6b8c23a03 | Jean | Mathews | 2010-06-06 ff8720d4-f808-4ee6-90e6-649872fdfa55 | Janis | Bunch | 2010-03-12 ff48d89b-6afe-4ba0-8539-9683bec62c89 | Sandy | Yashnyk | 2010-04-25 ff48d2a4-0637-4e46-9461-3dd0dc0d4d83 | Kendra| Elliott | 2010-05-09 ff3a2a14-2575-44d5-b40b-3780f4d2506a | Kay | Maher | 2010-04-20 fef7625b-d1e1-4c1a-bc82-d35a4a6db16d | Carolyn | Woodul | 2010-04-05 fef21bbb-07a0-4c84-8708-4dc41b8b770b | Laurie| Montijo | 2010-04-03 feee6473-af4d-4e70-b20c-a74ba08c000f | Geneva| Anderson| 2010-04-03 feb690fc-0afb-4e87-b0d1-bdb2c4603fd1 | Judith| Astroff | 2010-06-05 fea0f9a6-e89f-4dbd-b3fd-83efed27221f | Jennifer | Lavigne | 2010-02-09 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-03-20 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-03-27 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-03 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-10 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-17 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-25 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-05-01 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-05-08 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-05-16 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-05-22 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-05-30 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-06-06 fe825a6d-6820-4282-b8e9-2e3cb9f660e8 | Susan | Stowe | 2010-03-12 fe825a6d-6820-4282-b8e9-2e3cb9f660e8 | Susan | Stowe | 2010-03-15 But in John Smith's case where he has more than 5 entries, I would like query results to limit him to just 5 entries to look like this: username | firstname | lastname | signedup --+---+-+--- - ffc4bd0a-ccff-4203-a03c-4bd6b8c23a03 | Jean | Mathews | 2010-03-13 ffc4bd0a-ccff-4203-a03c-4bd6b8c23a03 | Jean | Mathews | 2010-05-07 ffc4bd0a-ccff-4203-a03c-4bd6b8c23a03 | Jean | Mathews | 2010-06-06 ff8720d4-f808-4ee6-90e6-649872fdfa55 | Janis | Bunch | 2010-03-12 ff48d89b-6afe-4ba0-8539-9683bec62c89 | Sandy | Yashnyk | 2010-04-25 ff48d2a4-0637-4e46-9461-3dd0dc0d4d83 | Kendra| Elliott | 2010-05-09 ff3a2a14-2575-44d5-b40b-3780f4d2506a | Kay | Maher | 2010-04-20 fef7625b-d1e1-4c1a-bc82-d35a4a6db16d | Carolyn | Woodul | 2010-04-05 fef21bbb-07a0-4c84-8708-4dc41b8b770b | Laurie| Montijo | 2010-04-03 feee6473-af4d-4e70-b20c-a74ba08c000f | Geneva| Anderson| 2010-04-03 feb690fc-0afb-4e87-b0d1-bdb2c4603fd1 | Judith| Astroff | 2010-06-05 fea0f9a6-e89f-4dbd-b3fd-83efed27221f | Jennifer | Lavigne | 2010-02-09 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-03-20 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-03-27 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-03 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-10 fea0334e-4ae1-4599-b24d-9a5d8ce4fd37 | John | Smith | 2010-04-17 fe825a6d-6820-4282-b8e9-2e3cb9f660e8 | Susan | Stowe | 2010-03-12 fe825a6d-6820-4282-b8e9-2e3cb9f660e8 | Susan | Stowe | 2010-03-15 The username is unique for each user. pg version 8.25 on RHEL Any help in this would be greatly appreciated. Thank you. -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
