Unique Key
1. A unique key can allow null values. (You can define a unique key on columns that allow nulls.)
2. Each table can have multiple unique keys.
3. On some RDBMS A unique key automatically generates a non-clustered table index by default.
Read more about Unique Key: Defining Unique Keys, Surrogate Keys, Alternate Key
Famous quotes containing the words unique and/or key:
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—Samuel Beckett (1906–1989)
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