SURROGATE KEY
\sˈʌɹəɡˌe͡ɪt kˈiː], \sˈʌɹəɡˌeɪt kˈiː], \s_ˈʌ_ɹ_ə_ɡ_ˌeɪ_t k_ˈiː]\
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A unique primary key generated by the RDBMSthat is not derived from any data in the database and whoseonly significance is to act as the primary key.A surrogate key is frequently a sequential number (e.g. aSybase "identity column") but doesn't have to be. Havingthe key independent of all other columns insulates thedatabase relationships from changes in data values or databasedesign and guarantees uniqueness.Some database designers use surrogate keys religiouslyregardless of the suitability of other candidate keys.However, if a good key already exists, the addition of asurrogate key will merely slow down access, particularly if itis indexed.Compare: intelligent key.
By Denis Howe
Word of the day
basidiomycota
- comprises fungi bearing the spores on basidium: Gasteromycetes (puffballs); Tiliomycetes (comprising orders Ustilaginales (smuts) and Uredinales (rusts)); Hymenomycetes (mushrooms; toadstools; agarics; bracket fungi); in some classification systems considered a division of kingdom comprises fungi bearing spores on a basidium; includes Gasteromycetes (puffballs) Tiliomycetes comprising the orders Ustilaginales (smuts) and Uredinales (rusts) Hymenomycetes (mushrooms, toadstools, agarics bracket fungi).