DROP_EXISTING Clause of CREATE index

Rebuild the Clustered Index in a Single Step

Because of the dependency of nonclustered indexes on the clustered index, rebuilding the clustered index as separate DROP INDEX AND CREATE statements causes all the nonclustered indexes to be rebuilt twice. To Avoid this, use the DROP_EXISTING clause of the CREATE INDEX statement to rebuild the clustered index in a single atomic step. Similary, you can also use the DROP_EXISTING clause with a nonclustered index.