资料来源 : Free On-Line Dictionary of Computing

surrogate key
     
         A unique {primary key} generated by the {RDBMS}
        that is not derived from any data in the database and whose
        only significance is to act as the primary key.
     
        A surrogate key is frequently a sequential number (e.g. a
        {Sybase} "{identity column}") but doesn't have to be.  Having
        the key independent of all other columns insulates the
        database relationships from changes in data values or database
        design and guarantees uniqueness.
     
        Some database designers use surrogate keys religiously
        regardless of the suitability of other {candidate keys}.
        However, if a good key already exists, the addition of a
        surrogate key will merely slow down access, particularly if it
        is indexed.
     
        Compare: {intelligent key}.
     
        (1999-12-07)