Differences between Clustered vs Nonclustered Indexes in SQL Server

Should you use a clustered or a nonclustered index?

When starting out with SQL, you might intuitively know that you should add an index to a table, but you might not be sure what kind of index to add.

In this video we go over the basics of clustered and nonclustered indexes to help you get through index choice paralysis.

Blog post with example queries:

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[rondabrown]

Finally someone that explains by using realistic and relate-able scenarios...I actually get it now! Thanks

[emiliamatrejek]

I went through all videos on YouTube regarding this topic and finally that's the one that makes it clear to me. Many thanks!

[shaoyizhang]

The mushroom book example is very helpful. Thank you!

[andyqueiroz]

The better explanation ever found in the hole that are databases

[rabes]

Dude, this video was 200x more effective than half of the Microsoft press 70-762 textbook. Thank you much!!

[MrShivanand]

finally, a guy on point.. this was perfect!!

[carloscepeda]

Man, you're my hero, I'm not a database guy but this was so perfectly understandable.

[galaxywalker]

Best explanation on index I have ever watched!

[gotchihaeyo]

At 7:40, I finally understood the nonclustered index. Thanks.

[elinanikolopoulou]

Best video i came across so far, for this topic. Great analogies

[fadimichael]

A very good video, only part is the example of the clustered index, in my opinion, should be a phone book or dictionary instead of textbook content as the clustered is physically sort/ordered the data, this example very much applied on the no-clustered index. Thanks.

[BoxerDogs]

Do you have a video that explains the differences between a table scan, index scan and an index seek and when SSMS will use each of these? If not, would you consider doing a video about this?

[BoxerDogs]

At 6:35 you give an analogy about a nonclustered index and a clustered index. If I understand what you are saying, are the following statements true:

- A nonclustered index is like an index at the back of a book, with page numbers (each page number is like a row identifier)
- A clustered Index is like an index at the back of a book, but no pages numbers (which would seem odd for a book to have)

[robertgaudreau]

Great Bert, very clear explanation on how to use the index.

[navedahmad]

Thanks! for explaining with practical examples

[cedrics]

Thanks man, I was searching for a good explanation of the differences between both, this was perfect!

[mehdizeynalov]

Thank you very much, would be good if some examples were added, maybe it's already there in next videos

[yoanadimitrova]

Thanks, blue eyes! That was helpful. Can you do a video on ColumnStore Indexes, please?

[anitha]

Indexes should not be used 1)on small tables 2)tables that have large batch updates or insert operations 3)not be used on tables with high number of null values4)columns that are frequently manipulated

[trishlasaxena]

this video is really helpful . I have a doubt. If I have defined clustered and non clustered index and we are inserting new row, it will add the newly added row in specific position and shift other rows as per clusterd index. So, how non clustered index is getting benefitted here on inserting new rows. And is that possible to have table without any clustered index.