Blog

START WITH CONNECT BY SQL

Oct 15 2013

The START WITH… CONNECT BY clause can be used to select data that has a hierarchical relationship such as manager to employee relationships. The root of the hierarchy is selected with the START WITH condition. In the example below from Oracle, the top level manager has an employee_id of 100. The output is sorted by […]

ROLLUP, CUBE, and GROUPING SETS

Oct 15 2013

The ROLLUP, CUBE, and GROUPING SETS operators are extensions of the GROUP BY clause. The GROUPING SET is the union of the aggregates based on the columns specified in each set in the grouping set. Multiple columns that are in inner parentheses in the GROUPING SETS list are treated as a single set. The following […]

Grails Domain Class Reload Issuing Count Query

Aug 08 2012

When a Grails domain class is reloaded after a change, the Hibernate plugin for Grails verifies the domain class reloaded successfully by calling its count() method. Unfortunately, while somewhat rare, it is possible to have a domain class mapped to a very large table (or a view that joins very large tables) where a count […]

Simple Bayesian Network Inference Using Netica and JavaBayes

Jun 07 2012

If you have ever needed to work with Bayesian networks and conditional probabilities, you may have searched around for some libraries you can use. This article describes how to use two libraries with Java API support – Netica and JavaBayes – to set up a simple Bayesian network and calculate inferences. Netica is a commercial product with support for multiple […]

Ext JS XTemplate Tips

May 15 2012

Ext JS is a powerful web framework that helps develop organized consistent applications. It adopts a Rich Client UI programming model that promotes component re-usability. One of the more powerful features of Ext JS is the XTemplate. This allows a developer to build custom components without having to do it all yourself through a custom […]