What is the difference between a clustered and a non-clustered index?

• Clustered Index:
• The data in the table is physically sorted based on the clustered index.
• Each table can have only one clustered index (usually the primary key).
• Fast for queries that involve range-based retrieval (e.g., BETWEEN or ORDER

BY).

• Non-Clustered Index:
• The data in the table is not physically sorted. The non-clustered index is

stored separately from the actual data.

• A table can have multiple non-clustered indexes.
• Faster for point lookups (single value queries) but less efficient for

range-based searches.