ChapterChapterTheRelationalCh2Ch2TheRelationalTheCAPNamingthePartsofaRelationalKeys,Superkeys,andNullRelationalSet-TheoreticNativeRelationalTheInterdependenceofIllustrativeOtherRelational DatabasePrinciples& 2.22.2NamingthePartsofaOld:fileofColumnnamesOld:fieldnamesofRowsOld:recordsofaOld:setof DatabasePrinciples& 2.22.2NamingthePartsofa（關系（表Fileof（屬性（列（元組（行（模式（表頭Typeof DatabasePrinciples& 2.22.2NamingthePartsofatable columnt 2tablerow

DatabasePrinciples& 2.32.3RelationalRule1.FirstNormalFormCan'thavemulti-valuedRule2.AccessRowsbyContentOnlyCan'tsay:thethirdrowdownfromtheNoordertotheNoordertotheRule3.TheUniqueRowEntityIntegrityRule(實體完整性 DatabasePrinciples& 2.42.4Keys,Superkeys,andNullKey&Primary DatabasePrinciples& 2.42.4Keys,Superkeys,andNullTheorem2.4.2.EverytableThasatleastoneProof.GivenatableTwithHead(T)={A1...KHead(T則K是表T的一個超鍵(superkey)While(K是表T的超鍵){THEN{K:=S;continue;}ELSEbreak;}Returnkey‘K’for DatabasePrinciples& 2.4Keys,Superkeys,andNull2.4Keys,Superkeys,andNull DatabasePrinciples& 2.52.5Relational languageintroducedbyE.F.storedintheformof

resultsofaqueryintableformoperationsofrelationalalgebra DatabasePrinciples& 2.5Relational2.5Relational(并∪R∪(交∩R∩(差–R–(乘積R DatabasePrinciples& nativerelational(投影R[R[Ai1,…,Aik(選擇RwhereRwhereRwhereA1=5(聯接R(除法RDifferencebetweenjoinandT=RT=R÷{B1,…,Bm{A1,A2,…,An DatabasePrinciples&

ArowtisinthetableRSifandonlytherearetworowsuinRandvinS,suchthatu[Bi]=v[Bi]foralli(1ik);t[Ai]=u[Ai]foralli,1int[Ci]=v[Ci]foralli,1imt[Bi]=u[Bi]=v[Bi]foralli,TcontainsthelargestpossiblesetofrowstsuchthatforeachrowsinS,wecanfindonerowrinR,wheret(Ai)=r(Ai)for1in s(Bj)=r(Bj)for1jmch2ch21：關系的合并運2：特殊運算（‘差’運算）的使用方3：‘除’運算與‘聯接’運算的區4：特殊運算（除算）的使用方

正確的表示方‘差‘除’運算與‘聯接’運算的區 查詢的結果關系稱為‘目標對象在決定某個元組t是否屬于結果關系ArowtisinthetableRSifandonlyiftherearetworowsuinRandvinS,suchthatu[Bi]=v[Bi]forallit[Ai]=u[Ai]foralli,1int[Ci]=v[Ci]foralli,1imt[Bi]=u[Bi]=v[Bi]foralli, DatabasePrinciples& DatabasePrinciples& ‘除’運算表達式的表示方‘被除數’關系中必須包含目標對象和條件對象’‘除數關系中只含‘條’ChapterBasicSQLQueryCh3Ch3BasicSQLQuerySettingUptheSimpleSelectUNIONOperatorsandFORALLSomeAdvancedSQLSetFunctionsinGroupsofRowsinACompleteDescriptionofSQLInsert,Update,andDelete DatabasePrinciples& BasicBasicDataTypeinSQLCREATESimpleSelectRelationalAlgebravsSQLQuerysingletable,product,naturaljoin,thetajointable&columnSimpleSELECTSQL查詢語句(Selectstatement)BETWEEN…ANDIS結果排序：ORDERSimpleSelectTheINexpr[NOT]IN(subquery fiedComparisonexprSOME|ANY|ALL(subqueryTheEXISTS[NOT]EXISTS(subqueryTheBETWEENexpr[NOT]BETWEENexpr1ANDSimpleSimpleSelectpredicateTheISNULLcolumnIS[NOT]TheLIKEcolumn[NOT]LIKEval1[ESCAPEval2underscore(_):anysinglepercent(%):anysequenceofzeroormorecharacters子查詢表名的作用獨立子查相關子查查詢謂 NOTSOME/ANY/ NOT復