What are included columns with respect to SQL Server indexing?
A new type of index was developed in SQL Server 2005 and beyond that assists in situations where a covering index is needed.
Indexes with Included Columns are non clustered indexes that have the following benefits:
1. Columns defined in the include statement, called non-key columns, are not counted in the number of columns by the database engine.
2. Columns that previously could not be used in queries, like nvarchar(max), can be included as a non-key column.
3. A maximum of 1023 additional columns can be used as non-key columns.