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Author: Kevin Feasel

Generating Code to Run Across All Databases via Dynamic SQL

Published 2022-10-12 by Kevin Feasel

Aaron Bertrand provides a warning around dynamic SQL:

For October’s T-SQL Tuesday, Steve Jones asks us to talk about ways we’ve used dynamic SQL to solve problems. Dynamic SQL gets a bad rap simply because, like a lot of tools, it can be abused. It doesn’t help that a lot of code samples out there show that “good enough” doesn’t meet the bar most of us have, especially in terms of security.

In a series I started last year, I talked about ways to do <X> to every <Y> inside a database, focusing on the example of refreshing every view (in a single database or across all databases). I already touched on what I want to dig into today: that it can be dangerous to try to parameterize things that can’t be parameterized in the ways people typically try.

Read the whole thing. I do find it funny how often people aren’t allowed to install well-known, third-party stored procedures (like Aaron’s sp_ineachdb) but it’s perfectly okay to write terrible code which is vulnerable to exploit because it was written in-house and is therefore more trustworthy somehow.

I don’t want to dunk on security teams too much in this regard, as I understand and really do appreciate the principle, though it often has counterintuitive first- and second-order consequences.

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Cross-Highlighting Power BI Charts

Published 2022-10-12 by Kevin Feasel

Marco Russo and Alberto Ferrari aren’t satisfied with a single date:

The best practice when we have multiple dates is to create a single, shared Date table and to connect it to all the date columns with different relationships. When a table has more than one date column, only one relationship can be active while the other relationships are inactive. In our sample model, the Date table connects both Sales[Order Date] and Sales[Delivery Date] with two relationships: one is active (with Order Date) and one is inactive (with Delivery Date).

Read on for a couple of options and what they mean for your visuals.

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Merge Joins in SQL Server

Published 2022-10-12 by Kevin Feasel

Jared Poche continues a series on join types:

Merge joins traverse both inputs once, advancing a row at a time and comparing the values from each input. Since they are in the same order, this is very efficient. We don’t have to pay the cost to create a hash table, and we don’t have the much larger number of index seeks nested loops would encounter.

Read the whole thing. Remember: merge joins are also the best strategy for when two lanes of the road come together.

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Case Operations in KQL

Published 2022-10-11 by Kevin Feasel

Robert Cain needs more than two paths for branching logic:

In my previous post Fun With KQL – IIF, we saw how to use the Kusto iif function to check for a condition then perform an action based on the result of a condition.

What if you had multiple conditions you need to check? While you could string multiple iif functions together there’s better solution: the KQL case function.

Robert includes several examples, as well as a check of whether KQL does short circuiting or not.

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Inserting Data into MySQL

Published 2022-10-11 by Kevin Feasel

Robert Sheldon takes us through data insertion in MySQL:

In most cases, adding a single row of data to table is a reasonably straightforward process. You define the INSERT clause and VALUES clause and usually specify the column list in between. The column list should include only those columns for which you provide values. The list can include the primary key column, generated columns, or columns defined with default constraints, but you must be careful how you handle them, as you’ll see later in the article.

This is definitely aimed at people new to MySQL and SQL in general.

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Implicit Conversion of DATEDIFF

Published 2022-10-11 by Kevin Feasel

Daniel Hutmacher noticed a problem:

As I was performance tuning a query, I found that a number of date calculation functions in SQL Server appear to be forcing a conversion of their date parameters to a specific datatype, adding computational work to a query that uses them. In programming terms, it seems that these functions do not have “overloads”, i.e. different code paths depending on the incoming datatype.

So let’s take a closer look at how this manifests itself.

Some of these results are pretty annoying, especially because I like to use DATETIME2(0) for the large majority of development work

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Column Lookups and Dynamic SQL

Published 2022-10-11 by Kevin Feasel

Rob Farley does a double-check:

I’ve written before about what I consider the golden rule with SQL Injection. And that is, to understand that DATA should not be executed like CODE. A parameter is fine – that’s not part of what gets executed – but you do not embed user-entered values into queries. You never create a WHERE clause like “WHERE t.col1 = 3”, if that value 3 is being passed in. Instead, you use “WHERE t.col1 = @param”. Because you can’t assume that “3” is safe to run.

But there are things in queries that can’t be parameterised. Table names, linked server names, column names, for example.

Read on to learn what Rob does in those cases.

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Auto-Aggregation on Dimension Tables: Gone

Published 2022-10-11 by Kevin Feasel

Matt Allington made the Power BI world a slightly better place:

Have you ever loaded a calendar table with lots of numeric columns (such as Year, Month Number, etc), loaded it into Power BI, and then had to manually go an turn off the default aggregation on these columns?  If you build Power BI reports, then I bet you have done this more than once. Jeffrey’s idea was that Power BI should be smart enough to detect a dimension table (one side of the relationship) and to disable these default aggregations.  There’s nothing worse than adding a Year column to a table and having Power BI add the years together. If I add a year to a table, I want to slice and dice, not SUM the years.

Matt added a request and see where that gets you.

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Creating Power BI Scorecards from Excel

Published 2022-10-11 by Kevin Feasel

Imke Feldmann has a goal:

I like Power BI scorecards a lot, as they give a really nice interface and look to your and your teams goals. However, entering all goals manually can become a bit tedious, especially if you have your goals already sitting in an Excel file. This is often the case for example with Budget figures. In this article I will share a method using Power Automate to create a scorecard automatically from an Excel file using standard Power Automate connectors. Please note that these connectors are still a bit limited, so connections to Power BI reports for example cannot be created currently.

Click through to see how.

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