I've tested both options (table1.id<>table2.id versus NOT table1.id=table2.id) on a table with 1042 polygons, and the time is exactly the same. Perhaps it will be differences with greater tables... The same test with the condition table1.id<table2.id (as Ufe noted) takes 7% less of time and it makes a table with half size than the the first query (<>) but then I cannot see at a glance the neibourhood of a selected polygon. For may porposes I need the first condition (<>)
Regards Sergi -----Mensaje original----- De: Peter Horsb�ll M�ller [mailto:[EMAIL PROTECTED] Enviado el: s�bado, 19 de marzo de 2005 9:00 Para: Uffe Kousgaard; Mapinfo-L Asunto: RE: MI-L 1-Listing neighbour polygons, 2-Ordering redistriction window Talking about cost, I have sometimes wondered what actually is fastes: where table1.id <> table2.id or where not table1.id = table2.id My guess is the later, but I'm not sure. Any ideas ? Peter Horsb�ll M�ller GIS Developer Geographical Information & IT COWI A/S Odensevej 95 5260 Odense S. Denmark Tel + 45 6311 4900 Dir +45 6311 4908 Mob +45 5156 1045 Fax + 45 6311 4949 E-mail [EMAIL PROTECTED] http://www.cowi.dk <http://www.cowi.dk/> ________________________________ From: Uffe Kousgaard [mailto:[EMAIL PROTECTED] Sent: Fri 18-Mar-05 16:41 To: Mapinfo-L Subject: Re: MI-L 1-Listing neighbour polygons, 2-Ordering redistriction window If A and B are neighbours then B and A are also neighbours. But it is more costly for the cpu to check both combinations. Regards Uffe ----- Original Message ----- From: "Gamiz Ribelles, Sergi (Regsa)" <[EMAIL PROTECTED]> To: "Mapinfo-list (E-mail)" <[email protected]> Sent: Friday, March 18, 2005 4:32 PM Subject: RE: MI-L 1-Listing neighbour polygons, 2-Ordering redistriction window The correct solution is select table1.id, table2.id (the same) from table1,table2 (the same) where table1.Obj intersects table2.Obj and table1.id<>table2.id (unidentity rather than minor) Sergi -----Mensaje original----- De: Uffe Kousgaard [mailto:[EMAIL PROTECTED] Enviado el: viernes, 18 de marzo de 2005 15:35 Para: Mapinfo-L Asunto: Re: MI-L 1-Listing neighbour polygons, 2-Ordering redistriction window ----- Original Message ----- From: "Gamiz Ribelles, Sergi (Regsa)" <[EMAIL PROTECTED]> To: "Mapinfo-list (E-mail)" <[email protected]> Sent: Friday, March 18, 2005 1:35 PM Subject: MI-L 1-Listing neighbour polygons, 2-Ordering redistriction window > Hello, > two q�estions: > 1- Does anyone know any tool or procedure to list out neighbour polygons (those that touch) to each other polygon of the same table? 1) Create a unique identifier (ID) for your table 2) Make a copy of your table 3) Run this SQL: select table1.id, table2.id from table1,table2 where table1.Obj intersects table2.Obj and table1.id<table2.id Regards Uffe --------------------------------------------------------------------- List hosting provided by Directions Magazine | www.directionsmag.com | To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] Message number: 15718 --------------------------------------------------------------------- List hosting provided by Directions Magazine | www.directionsmag.com | To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] Message number: 15720 --------------------------------------------------------------------- List hosting provided by Directions Magazine | www.directionsmag.com | To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] Message number: 15721 --------------------------------------------------------------------- List hosting provided by Directions Magazine | www.directionsmag.com | To unsubscribe, e-mail: [EMAIL PROTECTED] For additional commands, e-mail: [EMAIL PROTECTED] Message number: 15752
