The clustered index key columns are used by all nonclustered indexes internally as the means to locate rows in the table. So if you define a clustered index on a column x, and nonclustered indexes—one on column a, one on b, and one on c—your nonclustered indexes are internally created on column (a, x), (b, x), and (c, x), respectively.
- 2. Getting Started with the SELECT Statement
- from Training Kit (Exam 70-461): Querying Microsoft® SQL Server® 2012
- Publisher: Microsoft Press
- Released: December 2012
Clustered indices are combined with nonclustered indices when nonclustered indices are generated.
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