SQL Server Notification Services Question: Download SQL Notification Services PDF
Explain the difference between a primary key and a unique key?
Answer:
► Both are defined to ensure unique row.
► Primary key creates a clustered index on the column by default.
► Unique creates a non-clustered index by default.
► Primary key doesn't allow NULLs, but unique key allows one NULL only.
► Primary key creates a clustered index on the column by default.
► Unique creates a non-clustered index by default.
► Primary key doesn't allow NULLs, but unique key allows one NULL only.
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