More Order of Processing

Saving Master Keys

Calculating the Tally

Creating a large database

SQL Data Aggregation Aggravation

When we have to deal with and store a lot of data, it makes sense to aggregate it so that we store only the information we actually need. If we get this right, this works well, but the design of the system takes care and thought because the problems can be subtle and various. Joe Celko describes some of the ways that things can go wrong and end up providing incorrect, inaccurate or misleading results.

Temporary tables SCOPE

Statistics in SQL: The Mann–Whitney U test

Phil Factor shows how to use the Mann-Whitney U test in SQL to to find out whether two samples come from the same distribution.

The Order of Processing

Saving For Christmas

Statistics in SQL: The Kruskal–Wallis Test

Before you report your conclusions about your data, have you checked whether your 'actionable' figures occurred by chance? The Kruskal-Wallis test is a safe way of determining whether samples come from the same population, because it is simple and doesn't rely on a normal distribution in the population. This allows you a measure of confidence that your results are 'significant'. Phil Factor explains how to do it.