SQL Database Concepts Question: Download Basic SQL Server PDF
Can you please differentiate between a primary key and a unique key?
Answer:
- By default, clustered index on the column are created by the primary key whereas nonclustered index are created by unique key.
- Primary key doesn't allow NULLs, but unique key allows one NULL.
- Primary key doesn't allow NULLs, but unique key allows one NULL.
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