Strong and weak entities Astrong entityhas a primary key, meaning that it can be uniquely identified by its attributes alone. Aweak entityis an entity that can't be uniquely identified by its attributes alone. It is existence-dependent on its parent entity. It must use a f...
strong entities. weak entities. associative entities.all of these Most systems developers believe that data modeling is the least important part of the systems development process. (True/False) False 我們有專家為這個問題所編寫的解答! In an E-R diagram, there are ___ business rule(s) for ever...
To retrieve a segment, count every occurrence of every segment type in the path and proceed through the hierarchy according to the rules of navigation: ◆ Top to bottom ◆ Front to back (counting twin segments) ◆ Left to right For example, if an application program issues aGET-UNIQUE(GU)...
4.2Mapping weak entities 要有两个primary key,一个是strong relation的,一个是weak relation的。 Mapping weak entities For 1:1 relationship, we have a choice, and we prefer total to partial participation in order to minimize the number of NULL....
StrongNameKey Structure StructureCollection StructureInternal StructurePrivate StructureProtected StructurePublic StructureSealed StructureShortcut StyleBlock StyleSheet SubReport SubReportParamater Subscript Substitution SubtractFront SubtractMember SubtractMemberFormula SuggestedActionsExpander Summary SummaryView Supers...
Finally, based on a monotone increase or decrease of the membership of a subclass in its superclass, weak and strong class hierarchies are defined. Based possibility theory, Ma et al. [156] extend some major notions of the object-oriented databases for fuzzy information modeling, including ...
数据库系统概念(database system concepts)英文第六版 课后练习题 答案 第7章
StrongNameKey Structure StructureCollection StructureInternal StructurePrivate StructureProtected StructurePublic StructureSealed StructureShortcut StyleBlock StyleSheet SubReport SubReportParamater Subscript Substitution SubtractFront SubtractMember SubtractMemberFormula SuggestedActionsExpander Summary SummaryView Superscript ...
StrongHierarchy StrongNameKey Structure StructureCollection StructureInternal StructurePrivate StructureProtected StructurePublic StructureSealed StructureShortcut StyleBlock StyleSheet SubReport SubReportParamater Subscript Substitution SubtractFront SubtractMember SubtractMemberFormula SuggestedActionsExpander Summary Summary...
StrongNameKey Structure StructureCollection StructureInternal StructurePrivate StructureProtected StructurePublic StructureSealed StructureShortcut StyleBlock StyleSheet SubReport SubReportParamater Subscript Substitution SubtractFront SubtractMember SubtractMemberFormula SuggestedActionsExpander Summary SummaryView Superscript ...