![The primary key is the default clustered index in SQL Server and MySQL. This implies a 'clustered index penalty' on all non-clustered indexes. The primary key is the default clustered index in SQL Server and MySQL. This implies a 'clustered index penalty' on all non-clustered indexes.](https://use-the-index-luke.com/static/fig05_03_secondary_index_on_clustered_index.x1.A+AMD+Lr.png)
The primary key is the default clustered index in SQL Server and MySQL. This implies a 'clustered index penalty' on all non-clustered indexes.
![Does Dropping Primary Key Drop Non-Clustered Index on the Column? - Interview Question of the Week #085 - SQL Authority with Pinal Dave Does Dropping Primary Key Drop Non-Clustered Index on the Column? - Interview Question of the Week #085 - SQL Authority with Pinal Dave](https://blog.sqlauthority.com/i/c/nclpk1.jpg)
Does Dropping Primary Key Drop Non-Clustered Index on the Column? - Interview Question of the Week #085 - SQL Authority with Pinal Dave
![SQL SERVER - Identify Table Where Clustered Index is Not a Primary Key - DMV - SQL Authority with Pinal Dave SQL SERVER - Identify Table Where Clustered Index is Not a Primary Key - DMV - SQL Authority with Pinal Dave](https://blog.sqlauthority.com/wp-content/uploads/2016/04/clpk3.png)
SQL SERVER - Identify Table Where Clustered Index is Not a Primary Key - DMV - SQL Authority with Pinal Dave
![One Step To Understand Relationship Of Primary Key And Non-Clustered Indexes. – C-Sharp & SqlServer Key Concepts One Step To Understand Relationship Of Primary Key And Non-Clustered Indexes. – C-Sharp & SqlServer Key Concepts](https://rakeshmahur.files.wordpress.com/2014/12/32.jpg)