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Day: June 25, 2021

A Summary of Time Series Algorithms

Published 2021-06-25 by Kevin Feasel

Gavita Regunath and Dan Lantos give an overview of time series algorithms:

Time series forecasting is a data science task that is critical to a variety of activities within any business organisation. Time series forecasting is a useful tool that can help to understand how historical data influences the future. This is done by looking at past data, defining the patterns, and producing short or long-term predictions.

Click through for an overview, as well as ten examples of algorithms you can use for handling time series data.

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LAG() in SQL Server

Published 2021-06-25 by Kevin Feasel

Chad Callihan shows off one of the best window functions:

The LAG function in SQL Server allows you to work with a row of data as well as the previous row of data in a data set. When would that ever be useful? If you’re a sports fan, you’re familiar with this concept whether you realize it or not. Let’s look at an example.

LAG() is outstanding for business reports, such as if you want three-month trailing data.

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Moving Artifacts between Folders in Synapse Studio

Published 2021-06-25 by Kevin Feasel

Wolfgang Strasser looks at a recent update:

Another small but very powerful usability extension in Azure Synapse Studio was added at the beginning of June: Move artifacts across folders in Synapse Studio (without extra clicks but with drag&drop)

Once again, the release notes list contained the short sentence that made me curious… hmm… that sound nice… In one of my previous post, I described the “old” way of moving artifacts around in Synapse Studio.

Click through for a demonstration.

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SQL Server 2019 on CentOS 7.5 Issues

Published 2021-06-25 by Kevin Feasel

Aaron Bertrand recaps some recent installation issues:

I’ve created countless Docker containers running SQL Server since I first wrote about it back in 2016, but I recently had my first foray into configuring SQL Server 2019 on a real live Linux machine.

It did not go as smoothly as I expected, so I wanted to share the solution to a particular problem I haven’t seen described elsewhere.

First, let me retrace my steps.

Click through for a summary of the issues.

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Logging Database-Level Security Commands

Published 2021-06-25 by Kevin Feasel

Kenneth Fisher keeps the receipts:

In my last post I talked about reasons why your permissions might go missing. One of the reasons, and in my experience, one of the more unusual reasons, is that a command was run that changed the permissions. SQL doesn’t natively log these. Well, technically it does. They can be found in the default trace. But I don’t generally consider that to be terribly useful because on a busy server what’s available in the default trace may not last long. Regardless I ended up creating a DDL trigger to collect any database level security commands run. There are other ways to do this but for various reasons I decided to go with a trigger. Primarily because I could create one piece of code and cover every database in the instance.

Read on to learn how to create an appropriate table and a trigger to log that data.

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Column-Level Encryption and Hashing

Published 2021-06-25 by Kevin Feasel

Eric Rouach shows off a pair of things:

Using as an example the AdventureWorks2014 database, the first script describes the process of encrypting the “CardNumber” column from the Sales.CreditCard table while keeping the data decryptable.

Our pre-requisite is the creation of a Master Key, a Certificate and a Symmetric Key.

Once having those created, we may proceed to the addition of a new column called “CardNumberEnc” (where the suffix “Enc” stands for “Encrypted”). This column has a VARBINARY(250) Data Type and is nullable.

Read on for an example of using column-level encryption, followed by how you’d decrypt the data. Then, Eric discusses hashing, though I disagree with the nomenclature of “encryption and make the data non-decryptable.” The reason is that encryption is, by its nature, a two-way process and necessarily requires the ability to decrypt. Hashing, meanwhile, is a one-way process without a direct means of reversal. Nomenclature aside, the examples are good and I appreciate Eric using one of the larger SHA2 hashing algorithms rather than MD5.

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