Oh that was just an example...Let me make a real example: I have a table "Sensors" (that has to contain different sensor types) with a Value. That value doesn't have to be fixed, but I want to define it in a way that it changes its structure when the sensor type changes. For example, for Temperature sensor I would like to have just a float number, but for the humidity I could need of absolute and relative humidity (2 floats). I'd just like to know if I can say that the VALUE is a composite type...that I have then to specialize in Temp Type and Humidity type...using them in their particular case.
This procedure has a name...and it's the inheritance. As I understood, postgres allow me the table inheritance, but not the type inerithance. Here is an example about how this works on Oracle: http://www.oracle.com/technology/products/oracle9i/daily/jan29.html 2009/6/5 Rob Sargent <robjsarg...@gmail.com> > I'm not sure how Temperature and Humidity are related as types beyond > "extends float". i.e. What tuple definition could alternatively have a Temp > or a Humidity value? (I do understand their physical relationship :) ) > > > > > Gianvito Pio wrote: > >> Hi all, >> I just want to ask you if it's possible to define sub types in PostgreSQL >> (Type inheritance). I found that table inheritance is possible...but I'd >> like to do it on types. >> >> Example: >> define a type Value and two subtypes Temperature and Humidity and then >> define a table that has an attribute of Value type (that can accept both >> specialized types). >> >> Thanks >> > > > -- > Sent via pgsql-sql mailing list (pgsql-sql@postgresql.org) > To make changes to your subscription: > http://www.postgresql.org/mailpref/pgsql-sql >
