Can we apply non clustered index on primary key?

Can we apply non clustered index on primary key?

Indexes and Constraints Indexes are automatically created when PRIMARY KEY and UNIQUE constraints are defined on table columns. For example, when you create a table with a UNIQUE constraint, Database Engine automatically creates a nonclustered index.

What is non clustered index?

A non-clustered index (or regular b-tree index) is an index where the order of the rows does not match the physical order of the actual data. In a non-clustered index, the leaf pages of the index do not contain any actual data, but instead contain pointers to the actual data.

Is it good to have PK index for primary key?

But the fact that you can create another doesn’t indicate that the PK index doesn’t also already exist. The additional index does no good, but the only harm (very small) is the additional file size and row-creation overhead. As everyone else have already said, primary keys are automatically indexed.

Can a unique index be created without a primary key?

Declaring a PRIMARY KEY or UNIQUE constraint causes SQL Server to automatically create an index. An unique index can be created without matching a constraint, but a constraint (either primary key or unique) cannot exist without having a unique index.

How to keep the unique index even after we disabled the PK constraint?

This is very helpful! “using index” will create a unique index with the same name as the PK constraint, but when we disable the constraint, the unique index is also gone. My another question is that how we keep the unique index even after we disabled the pk constraint?

Which is an example of a clustered PK?

Genders or InvoiceTypes or PaymentType are another example of tables that should be clustered by its PK (because you’ll usually join them on GenderId, InvoiceTypeId or PaymentTypeId). When a clustered index is deemed to be more beneficial to the overall system than a clustered PK by using some measure of performance.