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Statistics in SQL: Student’s t-test

Many undergraduates have misunderstood the name 'Students' in the t-test to imply that it was designed as a simple test suitable for students. In fact it was William Sealy Gosset, an Englishman publishing under the pseudonym Student, who developed the t-test and t distribution in 1908, as a way of making confident predictions from small sample sizes of normally-distributed variables. As Gosset's employer was Guinness, the brewer, Phil Factor takes a sober view of calculating it in SQL.… Read more

Encrypting connection strings in web.config

Encrypting web.config elements is a good security feature. Web.Config elements can include passwords and important keys that we need to protect.Encrypting web.config elements is a good security feature. Web.Config elements can include passwords and important keys that we need to protect. There are several methods to encrypt the web.config: Using a command line statement Using … Read more

Morphing the Monolith

Microservices can certainly be made to work well for particular types of applications, but is it relevant to the mainstream? Can it replace the traditional architectures of database-driven applications? Microservice architecture is a type of service-oriented architecture that was developed from the concept of Domain-Driven design (DDD) and consists of loosely-coupled services that are network-based. … Read more

Is It Time To Stop Using IsNumeric()?

The old system function IsNumeric() often causes exasperation to a developer who is unfamiliar with the quirks of Transact SQL. It seems to think a comma or a number with a 'D' in the midde of it is a number. Phil Factor explains that though IsNumeric has its bugs, it real vice is that it doesn't tell you which of the numeric datatypes the string parameter can be coerced into, and because it doesn't check for overflow. Phil comes to the rescue with a couple of useful alternatives, one of which works whatever version of SQL Server you have, and which tell you what datatype the string can be converted to.… Read more

Working From Home

The idea that one can do nothing useful as a developer unless you are in an open plan office is rather retro. Although we all get that knowing wink when we announce that we are “Working from Home”, the truth is more complicated, I think. Some people are more productive when they work from home, … Read more

Filtering Errors in PowerBI

I just faced this problem when trying to analyze some information from google analytics in PowerBI. In my specific situation, I was trying to extract a number from some URL querystrings and filter the rows without the number. When I set the data type of the column to decimal, the rows without a number receive … Read more

To Fly, To Serve, To Fry Your Servers

So, the story goes that an Ops engineer walked into a data center with the necessary pass, a cheery wave and a ‘good morning’. Shortly afterwards, he made history. At around 8.30AM, British Airway’s entire communications systems went down at the height of the May holiday, forcing them to cancel flights from the UK’s two … Read more

News for Differential Backup

SQL Server 2017 brings several improvements to us. Sometimes a simple new field in a DMV can turn possible interesting new functionalities. That’s what happens with differential backup in SQL Server 2017. The DMV sys.dm_db_file_space_usage has a new field: modified_extent_page_count . This new field tell us how many pages were changed since the last full backup. … Read more

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.… Read more

WannaCry Over Spilled Data

The WannaCry ransomware attack has highlighted a serious problem. If there is negligence in your IT strategy, you are increasingly risking the functioning of your organisation, and the privacy of your customers. If you are being careless with data you don’t own, and of which you are legally only the custodian, if you are storing … Read more

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