A database term.
A secondary key is used to locate one (or more) records within a database. Sometimes called an 'alternative key'
It is different from the 'primary key' because a primary key is guaranteed to return a single record whereas a secondary key may return more than one record.
Example: A database contains a table of employee names and each employee has a primary key that uniquely identifies them, a secondary key could be used to return all records of people with the surname 'Jones'.
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