I have read this. -
Clustered index are those in which data is arranged on fields so that it act as an index. like the phonebook. And in non-clustered index we make a new index outside and data and indexes are at different places like book index at the back.
And this also . - primary index ( clustered ) secondary ( non-clustered)
so if the primary is clustered this means the index should not be present outside. But we many time implement the index outside in primary index does it not make it non-clustered ?
If primary index is a clustred index then what is clustred index that states that make a entry for unique keys only. Are they both the same?