A Difference Between ISNULL And COALESCE You Might Care About In SQL Server

Опубликовано: 23 Март 2026
на канале: Erik Darling (Erik Darling Data)

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In this video, I delve into the subtle yet significant differences between 'ISNULL' and 'COALESCE' in SQL Server queries, focusing on their practical implications rather than just theoretical performance. Erik Darling from Darling Data shares his insights, emphasizing that while both functions are useful for handling null values, 'ISNULL' offers a unique advantage by potentially skipping unnecessary checks when the column is guaranteed to not be nullable. The video also touches on the broader context of SQL Server maintenance and consulting services, offering viewers low-cost ways to support the channel and highlighting upcoming speaking engagements at Data Saturday Dialist and Past Data Summit in Seattle. By exploring these topics, I aim to provide practical advice that can help developers write more efficient and maintainable queries.

CHAPTERS

00:00:00 - Introduction
00:00:29 - About the Channel
00:01:12 - Consulting Services
00:01:30 - Training Offerings
00:02:02 - Upcoming Events
00:02:23 - IsNull vs Coalesce
00:02:40 - Performance Tests
00:03:05 - Superpowers of IsNull
00:03:16 - Coalesce as Case Expression
00:03:49 - Query Plan Example
00:04:35 - Index Seek with IsNull
00:05:34 - Query Plan Analysis
00:07:19 - Conclusion
00:08:25 - Join and Where Clause Advice

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