one clustered index per table

一個資料表只能有一個叢集索引

備註:
一個資料表可以有多個非叢集索引(nonclustered indexes)

In SQL Server, indexes are organized as B-trees.
Nonclustered indexes have the same B-tree structure as clustered indexes,
https://technet.microsoft.com/en-us/library/ms177443(v=sql.105).aspx


ref:
Clustered Index Structures
Nonclustered Index Structures