Unique identifier

{{Hatnote|Not to be confused with the [[UID (disambiguation)#In computing|many systems of unique identifiers]], many of which have non-unique proper names such as Unique Identifier, UID, or Unique Identification Number.}}

{{Hatnote|Not to be confused with the [[UID (disambiguation)#In computing|many systems of unique identifiers]], many of which have non-unique proper names such as Unique Identifier, UID, or Unique Identification Number.}}

A '''unique identifier''' ('''UID''') is an [[identifier]] that is guaranteed to be unique among all identifiers used for those objects and for a specific purpose.<ref name="identifiers">{{cite journal | doi=10.1371/JOURNAL.PBIO.2001414 | doi-access=free | title=Identifiers for the 21st century: How to design, provision, and reuse persistent identifiers to maximize utility and impact of life science data | date=2017 | last1=McMurry | first1=Julie A. | last2=Juty | first2=Nick | last3=Blomberg | first3=Niklas | last4=Burdett | first4=Tony | last5=Conlin | first5=Tom | last6=Conte | first6=Nathalie | last7=Courtot | first7=Mélanie | last8=Deck | first8=John | last9=Dumontier | first9=Michel | last10=Fellows | first10=Donal K. | last11=Gonzalez-Beltran | first11=Alejandra | last12=Gormanns | first12=Philipp | last13=Grethe | first13=Jeffrey | last14=Hastings | first14=Janna | last15=Hériché | first15=Jean-Karim | last16=Hermjakob | first16=Henning | last17=Ison | first17=Jon C. | last18=Jimenez | first18=Rafael C. | last19=Jupp | first19=Simon | last20=Kunze | first20=John | last21=Laibe | first21=Camille | last22=Le Novère | first22=Nicolas | last23=Malone | first23=James | last24=Martin | first24=Maria Jesus | last25=McEntyre | first25=Johanna R. | last26=Morris | first26=Chris | last27=Muilu | first27=Juha | last28=Müller | first28=Wolfgang | last29=Rocca-Serra | first29=Philippe | last30=Sansone | first30=Susanna-Assunta | journal=PLOS Biology | volume=15 | issue=6 | pages=e2001414 | pmid=28662064 | pmc=5490878 | display-authors=1 }}</ref> The concept was formalized early in the development of [[computer science]] and [[information system]]s. In general, it was associated with an [[primitive data type|atomic data type]].

[[Australia|A]] '''unique identifier''' ('''UID''') is an [[identifier]] that is guaranteed to be unique among all identifiers used for those objects and for a specific purpose.<ref name="identifiers">{{cite journal | doi=10.1371/JOURNAL.PBIO.2001414 | doi-access=free | title=Identifiers for the 21st century: How to design, provision, and reuse persistent identifiers to maximize utility and impact of life science data | date=2017 | last1=McMurry | first1=Julie A. | last2=Juty | first2=Nick | last3=Blomberg | first3=Niklas | last4=Burdett | first4=Tony | last5=Conlin | first5=Tom | last6=Conte | first6=Nathalie | last7=Courtot | first7=Mélanie | last8=Deck | first8=John | last9=Dumontier | first9=Michel | last10=Fellows | first10=Donal K. | last11=Gonzalez-Beltran | first11=Alejandra | last12=Gormanns | first12=Philipp | last13=Grethe | first13=Jeffrey | last14=Hastings | first14=Janna | last15=Hériché | first15=Jean-Karim | last16=Hermjakob | first16=Henning | last17=Ison | first17=Jon C. | last18=Jimenez | first18=Rafael C. | last19=Jupp | first19=Simon | last20=Kunze | first20=John | last21=Laibe | first21=Camille | last22=Le Novère | first22=Nicolas | last23=Malone | first23=James | last24=Martin | first24=Maria Jesus | last25=McEntyre | first25=Johanna R. | last26=Morris | first26=Chris | last27=Muilu | first27=Juha | last28=Müller | first28=Wolfgang | last29=Rocca-Serra | first29=Philippe | last30=Sansone | first30=Susanna-Assunta | journal=PLOS Biology | volume=15 | issue=6 | pages=e2001414 | pmid=28662064 | pmc=5490878 | display-authors=1 }}</ref> The concept was formalized early in the development of [[computer science]] and [[information system]]s. In general, it was associated with an [[primitive data type|atomic data type]].

In [[relational database]]s, certain attributes of an [[entity–relationship model|entity]] that serve as unique identifiers are called ''[[primary key]]s''.<ref name="JurDfg">{{Cite book |last1=Kline |first1=Kevin E. |last2=Kline |first2=Daniel |last3=Hunt |first3=Brand |date=2009 |title=SQL in a nutshell |location=Beijing |publisher=O'Reilly |edition=3rd |isbn=978-0-596-51884-4 |oclc=244652620}}</ref>

In [[relational database]]s, certain attributes of an [[entity–relationship model|entity]] that serve as unique identifiers are called ''[[primary key]]s''.<ref name="JurDfg">{{Cite book |last1=Kline |first1=Kevin E. |last2=Kline |first2=Daniel |last3=Hunt |first3=Brand |date=2009 |title=SQL in a nutshell |location=Beijing |publisher=O'Reilly |edition=3rd |isbn=978-0-596-51884-4 |oclc=244652620}}</ref>