Posts tagged domain
It was fairly difficult to come up with a title for this article that sort of covers the content. To me it is quite clear what this is about – but how to convey that in a title? Let me explain: today in our project we discussed the implementation of a data service. The service operation under scrutiny takes a city as input and returns a list all open orders from customers located in that city. Nothing very special there. The interesting complication lies in the fact that the customers are part of a different domain than the orders. This means – under our architecture guidelines – that we cannot create a single SQL query that joins together the customers table with the orders table. A database link to join the tables across databases is out of the question and even if these tables currently reside in the same database – such a join is not allowed. Different data domains are treated as independent entities and no direct dependencies between the two should be created. Every design has pass the check ‘will it still work if one of the domains involved were to be relocated to the cloud or be replaced by a third party application’.
The architecture is service oriented. Every domain More >
Retrieving the values for domains in SQL queries in the Oracle RDBMS – months, days, numbers and custom value sets1
It happens quite frequently that in our database applications – in queries or in PL/SQL packages – we need to use the values from more or less standard domains or custom lists of values. For example the list of all months in the year – to show a breakdown list of some measure per month. Or the days of the week, to do something similar. Sometimes we just need a list of numbers in a certain range. And it is quite common to outer join such a collection of domain values with the set of measurements, using the partition outer join feature – to ensure that for each category of measurements, there is an aggregate for each of the values in the domain.
This article demonstrates several examples of standard domains, some SQL tricks for composing domains out of thin air and a number of features to spell out numbers and internationalize days and month names.