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What is the difference between primary key & unique index ?
Answer:
Primary : a relational database constraint. Primary key consists of one or more columns that uniquely identify a row in the table. For a normalized relation, there is one designated primary key.
Unique index: a physical object that stores only unique values. There can be one or more unique indexes on a table
Unique index: a physical object that stores only unique values. There can be one or more unique indexes on a table
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