ISO/IEC 19075-2:2021

INTERNATIONAL ISO/IEC
STANDARD 19075-2
First edition
2021-08
Information technology — Guidance
for the use of database language
SQL —
Part 2:
Time-related information
Technologies de l'information — Recommandations pour l'utilisation
du langage de base de données SQL —
Partie 2: Informations d'horodatage
Reference number
©
ISO/IEC 2021
© ISO/IEC 2021
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ii © ISO/IEC 2021 – All rights reserved

ISO/IEC19075-2:2021(E)
Contents Page
Foreword.vi
Introduction.viii
1 Scope.1
2 Normativereferences.2
3 Termsanddefinitions.3
4 Time-relateddatatypes,constructs,operators,andpredicates.4
4.1 Contextoftime-relatedspecifications.4
4.2 Datetimetypes.4
4.3 DateTimeliterals.6
4.4 Intervaltypes.7
4.5 Interval literals.8
4.6 Periods.9
4.7 Operationsinvolvingdatetimesandintervals.10
4.8 Time-relatedpredicates.10
4.8.1 Overlaps predicate.10
4.8.2 Period predicates.11
5 Time-relatedtables.14
5.1 Introductiontotime-relatedtables.14
5.2 Application-timeperiodtables.14
5.2.1 Introductiontoapplication-timeperiodtables.14
5.2.2 Extensionstoprimarykey/uniqueconstraints.14
5.2.3 Extensionstoreferentialconstraints.15
5.2.4 Insertingrowsintotablescontaininganapplication-timeperioddefinition.18
5.2.5 Updatingrowsoftablescontaininganapplication-timeperioddefinition.18
5.2.6 Updatingthetablebetweenspecificpointsintime.19
5.2.7 Deletingrowsfromtablescontaininganapplication-timeperioddefinition.22
5.2.8 Deletingrowsbetweenspecificpointsintime.22
5.2.9 Queryingtablescontainingaperioddefinition.24
5.2.10 Addingaperioddefinitiontoatable.25
5.3 System-versionedtables.26
5.3.1 Introductiontosystem-versionedtables.26
5.3.2 Primarykeyandreferentialconstraints.27
5.3.3 Updatingrowsinsystem-versionedtables.28
5.3.4 Deletingrowsinsystem-versionedtables.29
5.3.5 Queryingsystem-versionedtables.29
5.4 Bi-temporal tables.30
Bibliography.32
©ISO/IEC2021–Allrightsreserved iii

ISO/IEC19075-2:2021(E)
Index.33
iv ©ISO/IEC2021–Allrightsreserved

ISO/IEC19075-2:2021(E)
Tables
Table Page
1 Fieldsindatetimevalues.4
2 Mappingofdatetimefieldstodatetimedatatypes.5
3 Examplesofthedatetimedatatypes.6
4 Examplesofdatetimeliterals.6
5 Fieldsinyear-monthINTERVALvalues.7
6 Fieldsinday-timeINTERVALvalues.7
7 Examplesofday-timeINTERVALvalues.8
8 Examplesofintervalliterals.8
9 Validoperatorsinvolvingdatetimesandintervals.10
10 Exampledatatableempforprimarykeywithapplication-timeperiod.15
11 Exampledatatabledeptforforeignkeywithapplication-timeperiod.16
12 Exampledatatableempforforeignkeywithapplication-timeperiod.16
13 Contentoftableempafterinsertwithapplication-timeperiod.18
14 Contentoftableempbeforeupdatingarow.18
15 Contentoftableempafterupdatingarow.19
16 Contentoftableempbeforeupdatingtheapplication-timeperiodofarow.19
17 Contentoftableempafterupdatingtheapplication-timeperiodofarow.19
18 Contentoftableempbeforeupdatingarowforaninnerpartofaperiod.20
19 Contentoftableempafterupdatingarowforaninnerpartofaperiod.20
20 Contentoftableempbeforeupdatingarowforallofaperiod.20
21 Contentoftableempafterupdatingarowforallofaperiod.21
22 Contentoftableempbeforeupdatingtheedgeofaperiodofarow.21
23 Contentoftableempafterupdatingtheedgeofaperiodofarow.21
24 Contentoftableempbeforedeletinganinnerpartofaperiod.22
25 Contentoftableempwithapplication-timeperiodafterdeletinganinnerpartofaperiod.23
26 Contentoftableempwithapplication-timeperiodbeforedeletingarow.23
27 Contentoftableempbeforedeletinganedgeofaperiod.23
28 Contentoftableempafterdeletinganedgeofaperiod.24
29 Contentofsystem-versionedtableempbeforeupdatingarow.28
30 Contentofsystem-versionedtableempafterupdatingarow.28
31 Contentofsystem-versionedtableempbeforedeletingarow.29
32 Contentofsystem-versionedtableempafterdeletingarow.29
©ISO/IEC2021–Allrightsreserved v

ISO/IEC19075-2:2021(E)
Foreword
ISO(theInternationalOrganizationforStandardization)andIEC(theInternationalElectrotechnical
Commission)formthespecializedsystemforworldwidestandardization.Nationalbodiesthatare
membersofISOorIECparticipateinthedevelopmentofInternationalStandardsthroughtechnical
committeesestablishedbytherespectiveorganizationtodealwithparticularfieldsoftechnicalactivity.
ISOandIECtechnicalcommitteescollaborateinfieldsofmutualinterest.Otherinternationalorganizations,
governmentalandnon-governmental,inliaisonwithISOandIEC,alsotakepartinthework.
Theproceduresusedtodevelopthisdocumentandthoseintendedforitsfurthermaintenanceare
describedintheISO/IECDirectives,Part1.Inparticular,thedifferentapprovalcriterianeededforthe
differenttypesofdocumentshouldbenoted.Thisdocumentwasdraftedinaccordancewiththeeditorial
rulesoftheISO/IECDirectives,Part2(seewww.iso.org/directivesorwww.iec.ch/mem-
bers_experts/refdocs).
Attentionisdrawntothepossibilitythatsomeoftheelementsofthisdocumentmaybethesubjectof
patentrights.ISOandIECshallnotbeheldresponsibleforidentifyinganyorallsuchpatentrights.Details
ofanypatentrightsidentifiedduringthedevelopmentofthedocumentwillbeintheIntroductionand/or
ontheISOlistofpatentdeclarationsreceived(seewww.iso.org/patents),ortheIEClistofpatent
declarationsreceived(seepatents.iec.ch).
Anytradenameusedinthisdocumentisinformationgivenfortheconvenienceofusersanddoesnot
constituteanendorsement.
Foranexplanationofthevoluntarynatureofstandards,themeaningofISOspecifictermsandexpressions
relatedtoconformityassessment,aswellasinformationaboutISO’sadherencetotheWorldTrade
Organization(WTO)principlesintheTechnicalBarrierstoTrade(TBT)seewww.iso.org/iso/fore-
word.html.IntheIEC,seewww.iec.ch/understanding-standards.
ThisdocumentwaspreparedbyTechnicalCommitteeISO/IECJTC1,Informationtechnology,Subcom-
mitteeSC32,Datamanagementandinterchange.
ThisfirsteditionofISO/IEC19075-2cancelsandreplacesISO/IECTR19075-2:2015.
ThisdocumentisintendedtobeusedinconjunctionwiththefollowingeditionsofthepartsoftheISO/IEC
9075series:
— ISO/IEC9075-1,sixtheditionorlater;
— ISO/IEC9075-2,sixtheditionorlater;
— ISO/IEC9075-3,sixtheditionorlater;
— ISO/IEC9075-4,seventheditionorlater;
— ISO/IEC9075-9,fiftheditionorlater;
— ISO/IEC9075-10,fiftheditionorlater;
— ISO/IEC9075-11,fiftheditionorlater;
— ISO/IEC9075-13,fiftheditionorlater;
— ISO/IEC9075-14,sixtheditionorlater;
— ISO/IEC9075-15,secondeditionorlater;
— ISO/IEC9075-16,firsteditionorlater.
vi ©ISO/IEC2021–Allrightsreserved

ISO/IEC19075-2:2021(E)
AlistofallpartsintheISO/IEC19075seriescanbefoundontheISOandIECwebsites.
Anyfeedbackorquestionsonthisdocumentshouldbedirectedtotheuser’snationalstandardsbody.A
completelistingofthesebodiescanbefoundatwww.iso.org/members.htmlandwww.iec.ch/-
national-committees.
©ISO/IEC2021–Allrightsreserved vii

ISO/IEC19075-2:2021(E)
Introduction
Theorganizationofthisdocumentisasfollows:
1) Clause1,“Scope”,specifiesthescopeofthisdocument.
2) Clause2,“Normativereferences”,identifiesadditionalstandardsthat,throughreferenceinthis
document,constituteprovisionsofthisdocument.
3) Clause3,“Termsanddefinitions”,definesthetermsanddefinitionsusedinthisdocument.
4) Clause4,“Time-relateddatatypes,constructs,operators,andpredicates”,explainstime-relateddata
types,operators,andpredicatesinSQL.
5) Clause5,“Time-relatedtables”,explainshowtime-relatedtablesareused.
viii ©ISO/IEC2021–Allrightsreserved

INTERNATIONAL STANDARD ISO/IEC 19075-2:2021(E)
Informationtechnology—GuidancefortheuseofdatabaselanguageSQL—
Part2:
Time-relatedinformation
1 Scope
ThisdocumentdescribesthesupportinSQLfortime-relatedinformation.
ThisdocumentdiscussesthefollowingfeaturesoftheSQLlanguage:
— Time-relateddatatypes
— Operationsontime-relateddata
— Time-relatedPredicates
— Application-timeperiodtables
— System-versionedtables
— Bi-temporaltables
©ISO/IEC2021–Allrightsreserved 1

ISO/IEC19075-2:2021(E)
2 Normativereferences
Thefollowingdocumentsarereferredtointhetextinsuchawaythatsomeoralloftheircontentconsti-
tutesrequirementsofthisdocument.Fordatedreferences,onlytheeditioncitedapplies.Forundated
references,thelatesteditionofthereferenceddocument(includinganyamendments)applies.
ISO/IEC9075-1,Informationtechnology—Databaselanguages—SQL—Part1:Framework
(SQL/Framework)
ISO/IEC9075-2,Informationtechnology—Databaselanguages—SQL—Part2:Foundation
(SQL/Foundation)
2 ©ISO/IEC2021–Allrightsreserved

ISO/IEC19075-2:2021(E)
3 Termsanddefinitions
Forthepurposesofthisdocument,thetermsanddefinitionsgiveninISO/IEC9075-1apply.
ISOandIECmaintainterminologicaldatabasesforuseinstandardizationatthefollowingaddresses:
— IECElectropedia:availableathttp://www.electropedia.org/
— ISOOnlinebrowsingplatform:availableathttp://www.iso.org/obp
©ISO/IEC2021–Allrightsreserved 3

ISO/IEC19075-2:2021(E)
4 Time-relateddatatypes,constructs,operators,andpredicates
4.1 Contextoftime-relatedspecifications
TherequirementsforthematerialdiscussedinthisdocumentshallbeasspecifiedinISO/IEC9075-1
andISO/IEC9075-2.
4.2 Datetimetypes
ISO/IEC9075-2definesthetime-relateddatatypes,constructs,operators,andpredicatesdescribedin
thisdocument.ISO/IEC9075-2specifiesrequirementsforthematerialdiscussedinthisdocument.
Therearethreedatetimetypes,eachofwhichismadeupofdifferentdatetimefields.
AvalueofdatatypeTIMESTAMPismadeupofthedatetimefieldsYEAR,MONTH,DAY,HOUR,MINUTE,
andSECOND.ItisalwaysavalidtimeatavalidGregoriandate.
AvalueofdatatypeTIMEcomprisesvaluesofthedatetimefieldsHOUR,MINUTEandSECOND.Itis
alwaysavalidtimeofday.
AvalueofdatatypeDATEismadeupofthedatetimefieldsYEAR,MONTH,andDAY.Itisalwaysavalid
Gregoriandate.
TIMESTAMPandTIMEmaybespecifiedwithanumberof(decimal)digitsoffractionalsecondsprecision.
TIMESTAMPandTIMEmayalsobespecifiedasbeingWITHTIMEZONE,inwhichcaseeveryvaluehas
associatedwithitatimezonedisplacement(theoffsetoftheTIMESTAMPorTIMEfromCoördinated
UniversalTime,UTC).IncomparingvaluesofadatatypeWITHTIMEZONE,thevalueofthetimezone
displacementisdisregarded.
Table1,“Fieldsindatetimevalues”,specifiesthefieldsthatcanmakeupadatetimevalue.
Table1—Fieldsindatetimevalues
Keyword Meaning
YEAR Year,between0001and9999
MONTH Monthwithinyear,between01and12
DAY Daywithinmonth,between1and31,butfurtherconstrainedbythevalue
ofMONTHandYEARfields,accordingtotherulesforwell-formeddates
intheGregoriancalendar.
HOUR Hourwithinday,between00and23
MINUTE Minutewithinhour,between00and59
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ISO/IEC19075-2:2021(E)
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