A file is organized so that the ordering of the data records is the same as or close to the ordering of data entries in some index. Than that index is called
Clustered- this is the definition of clustered indexing and for the same reason a table can have only one clustered index.
yes sparse index also sequential
but there every record neednot get an entry
The Line is :" ordering of the data records is the same as or close to the ordering of data entries in some index "
The good example of clustering index is telephone directory
Where the index pages start with say "M". All entries in that pages is with M or N or we can say very close to M.
That is why it is clastering index as ans
(While only book is an example of unclustered index)