Non cluster Index in sql server

 A non-clustered index doesn’t sort the physical data inside the table. Which means non-clustered index contains the index key value and row locator that point to storage location of the table data. A table can have more than one non clustered index. It is created to improve the performance to get the fast result.

The index will have pointer to the storage location of the data. The pointer from an index row in a non-clustered index to a data row is called a row locator. Non-clustered index is also a binary tree but it doesn't create a physical order of rows. So the leave nodes of non-clustered index contain PK (if it exists) or row index. 

Inside the non-cluster index

Syntax to create non cluster index.

CREATE NONCLUSTERED INDEX <index_name>

ON <table_name> (<column_name> ASC/DESC)

We can have one or more columns in the index.

create nonclustered index IX_Person_Address on  person_Address (City)

See the index

We can create 999 non clustered index on a table.