Tim Mitchell

Tim Mitchell is a business intelligence consultant, author, and trainer. He has been building data solutions for over 20 years, and is a 13-time recipient of the Microsoft Data Platform MVP award (2010-2022). He is the founder and principal data architect at Tyleris Data Solutions.

Tim has spoken at international and local events including the SQL PASS Summit, SQLBits, SQL Connections, along with dozens of tech fests, code camps, and SQL Saturday events. He is the author of the book The SSIS Catalog: Install, Manage, Secure, and Monitor your Enterprise ETL Infrastructure, coauthor of the book SSIS Design Patterns, and is a contributing author on the charity book project MVP Deep Dives Vol 2.

You can visit his website and blog at TimMitchell.net or follow him on Bluesky at https://bsky.app/profile/tmitch.net.
  • Interests: SQL Server, Data Warehousing, ETL, Data Architecture, Python, Dbt

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Blog Post

SSIS Parameters

SSIS parameters help to ease the process of passing runtime values to SSIS packages. For values that can change over time, using parameters in SSIS is an ideal means...

2020-07-14 (first published: )

482 reads

Blog Post

Secure Your Data Prep Area

I’ve been building ETL processes for many years, and I’ve learned two universal truths: data preparation is messy, and you must always secure your data prep area. A data...

2020-06-18

9 reads

Blog Post

Lessons from Iowa’s Caucus Debacle

Earlier this week, the state of Iowa held its caucuses to choose each political party’s nominee for November’s presidential election. Being the first state in each election cycle to...

2020-02-11 (first published: )

786 reads

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Blogs

Giving AI Agents Visibility Into SQL Server with MCP

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I’ve been thinking a lot lately about what it actually takes to make an...

The Book of Redgate: Profits

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Redgate is a for-profit company. We look to make money by building and selling...

Session Materials for Techorama & DataGrillen 2026

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I’ve uploaded the slides for my Techorama session Microsoft Fabric for Dummies and my...

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Question of the Day

The string_agg function

We create the following table and then insert some records in it: 

create table t1 (
   id int primary key,
   category char(1) not null,
   product varchar(50)
);

insert into t1 values
(1, 'A', 'Product 1'),
(2, 'A', 'Product 2'),
(3, 'A', 'Product 3'),
(4, 'B', 'Product 4'),
(5, 'B', 'Product 5');
What happens if we execute the following query in both Sql Server and PostgreSQL? 
select id, 
category, 
string_agg(product, ';')
                 over (partition by category order by id
                 rows between unbounded preceding and unbounded following) as stragg
from t1;

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