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Day: February 25, 2021

Survival Analysis Notebooks

Published 2021-02-25 by Kevin Feasel

Dan Morris, et al, walk us through a survival analysis scenario:

In contrast to other methods that may seem similar on the surface, such as linear regression, survival analysis takes censoring into account. Censoring occurs when the start and/or end of a measured value is unknown. For example, suppose our historical data includes records for the two customers below. In the case of customer A, we know the precise duration of the subscription because the customer churned in December 2020. For customer B, we know that the contract started four months ago and is still active, but we do not know how much longer they will be a customer. This is an example of right censoring because we do not yet know the end date for the measured value. Right censoring is what we most commonly see with this form of analysis.

Click through for an intro as well as a half-dozen notebooks.

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Temporal Tables and Execution Plans

Published 2021-02-25 by Kevin Feasel

Hugo Kornelis starts a new sub-series within an existing series:

Welcome to part sixteen of the plansplaining series. The first of a few posts about how temporal tables affect execution plans. In this post, I’ll build on the last four posts on data modifications, building on the more generic discussion of data modification in the previous four posts. Later posts will look at data retrieval and some specific scenarios.

Hugo hits the highlights of temporal tables and how they handle insertion, deletion, and updating scenarios.

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Avoiding Division by Zero

Published 2021-02-25 by Kevin Feasel

Chad Callihan has a few methods for us to avoid dividing by zero:

In the real world, everyone knows that if you divide by zero a wormhole will open up and swallow the universe. In SQL Server, it’s not good, but it’s not nearly as dramatic. I encountered the following error this week and thought it would make a good topic:

Msg 8134, Level 16, State 1, Line 6
Divide by zero error encountered.

There are multiple ways to handle this error message in SQL Server and some are better than others. Let’s take a look at a few.

Click through for those methods and try to keep this universe existent—it’s where I keep all my stuff.

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