Select rows based on date in Oracle database
E.g. to select rows with a timestamp on minutes 0, 5, 10, …, 55 select * from t where mod(to_number(to_char(date_time_col, ‘mi’)),5)=0
Category Systems
How to alternately select m rows every n rows in oracle sql
For m=10 and n=100 add the following where clause WHERE mod(rownum, 100)
Sticking bicycle paths in CouchDB
In this installment of How To Stick Anything In CouchDB, I’ll take some bicycle path data released by the municipality of Copenhagen and stick them in CouchDB. As always I’m working in Terminal under Mac OS X. Bicycle paths in…
Free online O’Reilly book on CouchDB
Using shp2geocouch to push OSM data into geocouch
Today I installed the utility shp2geocouch on Mac OS X 1.6. First I needed to update RubyGems… sudo gem update –system Then I could install shp2geocouch sudo gem install shp2geocouch Next I downloaded OSM data for Copenhagen, Denmark wget …
Installing spatial databases on EC2
The spatial databases covered are PostGIS, MySQL spatial and MongoDB, Apache Cassandra. UPDATE: I’ll change this post or create a page to give the actual linux commands to run on the remote server. PostGIS on EC2 I have found a…
Building osm2pgsql on Mac OS X using homebrew
General instructions are here: Note: I’m running Snow Leopard (10.6.6 ) 1. Install homebrew Check that you don’t have it already: $ which brew If you don’t have <a href="http://mxcl.github.com/homebrew/">homebrew</a> install it from here: E.g. like this: $…
Using SQLite databases on different machines as a single virtual database
You can use separate SQLite database on different machines as a single virtual database by using the attach command in SQLite. I read about the technique here: For this example let’s use the simplest possible database. A contact database…
How to import OpenStreetMap data into PostgreSQL
1. Download data and software The instructions are fairly generic, so should work for both Windows, Linux and Mac OS X. I wrote them for Windows, but I’ve since then switched to Mac OS X. PostgreSQL+PostGIS I assume that you…
Google fusion tables cheat sheet
See below for commands using the Fusion Tables API. Example table is the oldschool message wall public table. Note that examples are shown first without the required url-encoding. Authenticating: Getting the auth token To authenticate you may use the following…