SQL Index -Index in SQL Server | Clustered Index in SQL Server | Non Clustered Index in SQL Server
Index is used to find the data quickly from table.
It is generally used on tables and views
it helps immensely to reduce time to find a data when index is on.
In case of no index will lead to a table scan. It is bad for performance.
Clustered index sort and store the data rows in the table or view based on their key values.
There can be only one clustered index per table, because the data rows themselves can be sorted in only one order.
Non Clustered index have a structure seperate from the table rows. A non-clustered index contains the
non clustered index key values and each key value has a pointer to the data row that contains the key value