Database Systems Final Exam Q And A

DATABASE SYSTEMS FINAL EXAM Q
AND A

SQLcf-cfanswer--iscfacfdomain-
specificcfprogrammingcflanguagecfdesignedcfforcfmanagingcfandcfcommunicatingcfwithcfd
atacfheldcfincfacfrelationalcfdatabasecfmanagementcfsystem

SQLcfiscfusedcffor:cf-cfanswer---creatingcfdatabases
-adding,cfmodifyingcfandcfdeletingcfdatabasecfstructures
-inserting,cfdeletingcfandcfmodifyingcfrecordscfincfdatabases
-queryingcfdatabases

DatacfDefinitioncfLanguagecf(DDL)cf-cfanswer--
usedcftocfcreatecfandcfmodifycfthecfstructurecfofcfthecfdatabasecf
example:cfCREATEcfALTERcforcfDROP

DatacfManipulationcfLanguagecf(DML)cf-cfanswer--
usedcftocfinsert,cfmodify,cfdeletecfandcfretrievecfdata
example:cfINSERTcfINTOcfUPDATEcforcfDELETE

DatacfRetrievalcfLanguagecf(DRL)cf-cfanswer--
usedcftocfquerycforcfretrievecfdatacffromcfacfdatabasecf
example:cfSELECT

DatacfControlcfLanguagecf(DCL)cf-cfanswer--usedcfforcfdatacfaccesscfcontrol

TransactioncfControlcfLanguagecf-cfanswer--usedcfforcfmanagingcfdatabasecftransactions

Keywordscf-cfanswer--
Thesecfhavecfacfverycfspecificcfmeaningcfincfthecflanguage.cfThecfstatementcfmustcfhavecfat
cfleastcfone.cfThesecfoftencfdefinecfthecfoperationcfthatcfiscfperformed



Identifierscf-cfanswer--
Thesecfrefercftocfthecfnamescfofcfthecftablescfandcfcolumnscfthatcfarecfcalledcforcfmanipulate
d

NullcfValuecf-cfanswer--
iscfacfmarkercfforcfdatacfthatcfhascfnotcfbeencfenteredcforcfiscfmissing,cfunknown,cforcfinapplic
able

NotcfNullcfConstraintcf-cfanswer--
iscfonlycfacfcolumncfconstraintcfandcfnotcfacftablecfconstraint;cfifcfyoucfdon'tcfspecifycfacf_____
,cfthecfcolumncfwillcfacceptcfnullcfvaluescfbycfdefault

UniquecfConstraintcf-cfanswer--forcescfeachcfvaluecfofcfacfcolumncforcftablecftocfbecfunique

, CheckcfConstraintcf-cfanswer--
allowscfforcflimitingcfacfparticularcfcolumncfbasedcfoncfacfparticularcfvaluecfrules
Thesecfinclude:
minimumcforcfmaximumcfvalue
specifiedcfvaluecf
rangecfofcfvalues

ALTERcftablecf-cfanswer--providescfthecfabilitycfto:
-add/dropcfacfcolumn
-altercfacfcolumn'scfdatacftype
-renamecfacfcolumn
-renamecfacftable
-add,cfaltercforcfdropcfacfcolumn'scfdefaultcfvaluecforcfnullcfabilitycfconstraint
-
add,cfaltercforcfdropcfcolumncforcftablecfconstraintscfsuchcfascfprimarycfkey,cfforeigncfkey,cfu
niquecfandcfcheckcfconstraint

SelectcfStatementcf-cfanswer--
iscfthecfbasiccfbuildingcfblockcfofcfanycfdatacfquerycfrequest.cfItcfiscfcommandcfthatcfpullscfspe
cificcfdatacffromcfacfparticularcftablecfwithincfthecfdatabasecfhighlighted

LimitcfStatementcf-cfanswer--itcflimitscfthecfnumbercfofcfrowscfthatcfarecfshown

OrdercfBycf-cfanswer--iscfusedcftocfsortcfbycfdatacfincfacfparticularcfcolumncforcfcolumns

SelectcfDistinctcf-cfanswer--eliminatescfduplicatecfvalues

Wherecf-cfanswer--
cancfbecfusedcfincfcombinationcfwithcfbooleancfcomparatorscfforcfcolumnscfthatcfarecfnumer
iccforcfintegers

Likecf-cfanswer--allowscftocffindcfsimilarcftext,cfbutcfiscfcasecfsensitive

%cf-cfanswer--wildcardcfplaceholdercfforcftextcfusedcfwithcfLIKEcforcfILIKEcfstatements

ILIKEcf-cfanswer--samecfascfLIKEcfstatementcfbutcfnotcfsensitivecftocfcapitalization

INcf-cfanswer--equivalentcftocfmultiplecfORcfstatements

Betweencf-cfanswer--cancfbecfusedcftocffindcfacfrangecfinsteadcfofcfusingcf>cfandcf<

NOTcf-cfanswer--cancfnegatecfIN,cfBetween,cfLIKEcforcfconditionalcfstatement

derivedcfcolumncf-cfanswer--
iscfthecfresultcfofcfacfcalculationcfandcfiscfcreatedcfwithcfacfSELECTcf---
cfclausecfexpressioncfthatcfiscfsomethingcfothercfthancfacfsimplecfreferencecftocfthecfcolumn



COALESCEcf-cfanswer--replacescfNULLcfvaluescfwithcfanothercfvalue