Do you want to rebuild or reorganize the index? Usually the rule of thumb (your mileage may vary) is that if the index is less than 30% fragmented you reorganize if it's greater than 30% you rebuild the index. A basic rebuild command would look something like this: ALTER INDEX [indexName] ON [SchemaName].[TableName] REBUILD; There are a number of options that you can do when rebuilding/reorganizing so I'd probably suggest reading up on the reference link below Reference:
https://msdn.microsoft.com/en-us/library/ms188388(v=sql.105).aspx Hope that helps!