Thread: ORDER BY question
Hope this is the correct forum - if not sorry. I have a query which returns a value of the form: '20010822.1338.1'. I would like to order the results, sorting : 1st: 20010822 2nd: 1338 3rd: 1 I can do this in perl, but have not found a way to do this using ORDER BY. I am VERY new to DB's; biologist trying to do informatics. Thanks. -- Chuck
On Thu, 15 Nov 2001 18:02:04 -0500 Charles Hauser <chauser@acpub.duke.edu> wrote: > Hope this is the correct forum - if not sorry. > > I have a query which returns a value of the form: '20010822.1338.1'. > > I would like to order the results, sorting : > > 1st: 20010822 > 2nd: 1338 > 3rd: 1 > > > I can do this in perl, but have not found a way to do this using ORDER BY. Hi,I'm supposing, for the sake of convenience, that a table including somerows is defined, and modeling a query which hassequential numbers(e.g. 1, 2, 3) to sort and SUBSTRINGs to divide the value into the threeparts. If your platform is PG,the query might goes well. BTW, a part of "select * from tbl where id < 3" depends on your query. create table tbl (id int4, tm text); insert into tbl values(1, '20010822.1338.1'); insert into tbl values(2, '20011121.2152.3'); insert into tbl values(3, '20011222.1338.1'); -- on v7.1.2 select t.dt from (select t1.id, 1 as rank, substring(t1.tm from 1 for 8) as dt from (select * from tbl whereid < 3) as t1 union all select t2.id, 2 , substring(t2.tm from 10 for 4) from (select* from tbl where id < 3) as t2 union all select t3.id, 3 , substring(t3.tm from 15 for 1) from (select * from tbl where id < 3) as t3 order by id, rank ) as t dt ----------20010822133812001112121523 (6 rows) Regards, Masaru Sugawara
-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 2001 November 15 06:02 pm, Charles Hauser wrote: > Hope this is the correct forum - if not sorry. > > I have a query which returns a value of the form: '20010822.1338.1'. > > I would like to order the results, sorting : > > 1st: 20010822 > 2nd: 1338 > 3rd: 1 > > > I can do this in perl, but have not found a way to do this using ORDER BY. It looks like you're encoding date and then two numeric data types into a single text string. Why? Not only is it inefficient from a storage perspective, but it will limit the flexibility (and value) of your data in the future. Solution? Redesign your database! CREATE TABLE foo ( first DATE NOT NULL,second INTEGER NOT NULL,third INTEGER NOT NULL,UNIQUE (first, second, third) ); The UNIQUE constraint implicitly creates an index on first, second and third, which will be used to do the sorting in the following query: SELECT * FROM foo ORDER BY first, second, third; And for some backwards compatibility, how about a VIEW... CREATE VIEW bar AS SELECT extract(year FROM first) ||extract(month FROM first) || extract(day FROM first) ||'.' || second|| '.' third AS baz FROM foo; - -- Andrew G. Hammond mailto:drew@xyzzy.dhs.org http://xyzzy.dhs.org/~drew/ 56 2A 54 EF 19 C0 3B 43 72 69 5B E3 69 5B A1 1F 613-389-5481 5CD3 62B0 254B DEB1 86E0 8959 093E F70A B457 84B1 "To blow recursion you must first blow recur" -- me -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.0.6 (GNU/Linux) Comment: For info see http://www.gnupg.org iEYEARECAAYFAjv8VzcACgkQCT73CrRXhLG2eQCfVsrBJrPxLJABsG7Z1Zva7jZf jWUAniScvuDkcqQVjyVCaeGhRIPzUPoV =ZQ7e -----END PGP SIGNATURE-----