What are the guidelines to decide which column to index?- Non-key columns can be dropped from a table only after the non-key index is dropped first.
- Columns can’t be defined in both the key column and the INCLUDE list.
- Non-key columns can be included only in non-clustered indexes.
- Column names can’t be repeated in the INCLUDE list.
- For Included Column Index to exist there must be at least one key column defined with a maximum of 16 key columns and 1023 included columns.