I’m excited to begin moving over courses from SQL Workbooks and making the material available here. The first course up for grabs is The Dirty Secrets of NOLOCK.

A Little Bit About the Course

What happens when you use NOLOCK hints in your code, or set your isolation level to READ UNCOMMITTED in SQL Server? In 50 minutes of online videos, you will learn what NOLOCK means, why NOLOCK can return incorrect results (and other problems), what allocation order scans are (and how to get them), and other risks and options for reading uncommitted data.

Course lessons include:

• What is NOLOCK? (3 minutes)
• The dirtiest secret: NOLOCK returns garbage data (10 minutes)
• The fast alternative to NOLOCK: indexing (5 minutes)
• Why NOLOCK is a misnomer (7 minutes)
• Bad phenomena that can occur under NOLOCK (2 minutes)
• Uses for NOLOCK: admin queries and garbage data (5 minutes)
• Allocation order scans (13 minutes)
• A common error with NOLOCK (6 minutes)

The Course Is Free, but Please Donate If You Find It Helpful

If you find my free courses helpful, show your appreciation by donating to one of the following organizations:

• Black Girls Code – whose mission is to “introduce programming and technology to a new generation of coders, coders who will become builders of technological innovation and of their own futures.”
• The Trevor Project – whose mission is to “end suicide among gay, lesbian, bisexual, transgender, queer & questioning young people.”
• The NAACP Legal Defense Fund – whose mission is to “achieve racial justice, equality, and an inclusive society.”
• The LGBTQ Victory Fund – which “works to change the face and voice of America’s politics and achieve equality for LGBTQ Americans by increasing the number of LGBTQ officials.”