Louis Davidson

Louis has been in the IT industry for over 20 years as a corporate database developer and data architect. Currently he is the Data Architect for CBN in Virginia Beach. Louis has been a Microsoft MVP since 2004, and is an active volunteer for the PASS locally and globally. He is the author of a series of SQL Server Database Design books, most recently Pro SQL Server Relational Database Design and Implementation.

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20 March 2021
20 March 2021

Determining actions you can take with Edge and Node tables in SQL Server

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One of the interesting things about working with many-to-many relationships in SQL Server with graph tables instead of a relational table is that unlike a relational many-to-many table, by default an edge may can implement relationships from lots of different tables (nodes). You can also limit what nodes can be related using which edges. For … Read more
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15 March 2021
15 March 2021

The Issue\Purpose of Multiple Edge Constraint/Conditions

Edge constraints were added in SQL Server 2019 to make the node to edge relationship stricter/enforced, and more like typical foreign key constraints. When used, they define what node types can be used in the from and to position of the edge. What makes edges different than a many-to-many relationship in a relational table is … Read more
12 March 2021
12 March 2021

Ways to get and deal with invalid node identifiers in SQL Server Edge references

One of the weirder things about graph tables in SQL Server is the mysterious backend implementation. The values you see when working with these objects look like this: {“type”:”node”,”schema”:”dbo”,”table”:”Node1″,”id”:0}, but when you get errors, you don’t see the json, you see what this represents (two integers for the object_id and unique id in the graph … Read more
26 October 2020
26 October 2020

Ignore the technology for a moment, let’s talk about the problem

Twelve and a half years ago I wrote my largest hit count article of my writing career Ten Common Database Design Mistakes. It currently shows as having over 1.2 million hits, despite having a misspelling in the first paragraph. After this length of time, you would think that things would have changed and we would … Read more
02 September 2020
02 September 2020

Weighted Randomization In T-SQL

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When I am not working on or writing about SQL, I am posting theme park pictures on Twitter of DisneyWorld (@DisneyPicADay) and Dollywood (@DollywoodP). The fun part of it is taking the pictures. The HARD part is deciding what to post every day. So instead of picking things from my head, I decided to harness … Read more
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17 April 2020
17 April 2020

SQL Agent Job Generator: Scheduling A Job

In this last entry in the initial series of posts on building a SQL Agent Job Generator, I am going to add the ability to schedule the jobs that we generated in the previous post. The code that is available here in github: https://github.com/drsqlgithub/SSISDeployTool/tree/e8c44505bba6b3c764531c8b489101b39b5c27a7, is likely sufficient for some smaller organization’s needs with jobs. (Future … Read more