SQL Server clustered index and non-clustered index instance

Create database myIndexDemo
Go
Use myIndexDemo
Go
Create table ABC
(
A int not null,
B char (10 ),
C varchar (10)
)
Go
Insert into ABC
Select 1, 'B', 'C'
Union
Select 5, 'B', 'C'
Union
Select 7, 'B', 'C'
Union
Select 9, 'B', 'C'
Go

Select * from ABC

-- Create a clustered index on the ABC table
Create clustered index CLU_ABC
On ABC ()
GO

-- View Indexes
Sp_helpIndex ABC

-- Insert data
Insert into ABC
Values (2, 'B', 'C ')

-- The physical structure of the entire table has changed because of clustered indexes.
-- The content queried Based on the index is:
Select * from abc with (index = CLU_ABC) where a> 1 and a <5

-- After the index is deleted
Drop index ABC. CLU_ABC

-- The physical order of the query content is still in order.
Select * from ABC


-- Create a non-clustered index on the ABC table
Create nonclustered index NONCLU_ABC
On ABC ()

-- View Indexes
Sp_helpIndex abc

-- Insert data
Insert into ABC
Values (4, 'B', 'C ')

-- The physical structure of the entire table has changed because of clustered indexes.
-- The query content is:
Select * from abc with (index = NONCLU_ABC)

-- After the index is deleted
Drop index ABC. NONCLU_ABC

-- The physical order of the query content is in the insert order.
Select * from ABC