it depends on what role this foreign key plays in your relation. if this foreign key is also a key attribute in your relation, then it can't be NULL if this foreign key is a normal attribute in your relation, then it can be NULL. Share Improve this answer Follow answered Jun 28, ...
For the following, answer whether Tables are in 3NF? If not, state the normalization rule that is violated. Rules can be: a. No multi-valued attribute. b. Not dependent on the whole primary key. c. De How would y...
In order to process large-scale diagrams, or many source codes automatically, formal and declarative representation is needed. In this paper, we propose automatic generation of documentation based on an attribute graph grammar.Takaaki GotoTetsuro Nishino...
摘要:Passenger contact in public transit (PT) networks can be a key mediate in the spreading of infectious diseases. This paper proposes a time-varying weighted PT encounter network to model the spreading of infectious diseases through the PT systems. Social activity contacts at both local and gl...
Entity Attribute Relationship ER Diagram Types Crow's Foot Notation DB Participation Types Interview End- Users Verbalize ER Diagram ER diagram model TypesLesson 5 Linking relational database tables Objective Link a primary key to a foreign key in a relational database systemLinking...
(1/2) where x and S are the concentrations of magnetic cations and donors,respectively.High Curie temperatures arise only when empty minority-spin or majority-spin d states lie at the Fermi level in the impurity band.The magnetic phase diagram includes regions of semiconducting and metallic ...
ssRNA is channeled through its multi- subunit ring-like core into the active site tunnel of its key exonuclease subunit Rrp44, which acts both as an enzyme and a motor. Even in isolation, Rrp44 can pull and sequentially cleave RNA nucleotides, one at a time, without any...
knowledge discovery in databases; decision trees; rule induction; attribute relevance analysis; 74.Hy-SN: Hyper-graph based semantic network 机译:Hy-SN:基于超图的语义网络 作者:Lu Zhen;Zuhua Jiang 期刊名称:《Knowledge-Based Systems》 | 2010年第8期 关键词: knowledge representation; semantic ne...
In this paper, we concentrate on detecting, pinpointing and suppressing potential testability weaknesses of a UML class diagram. The attribute significant from design testability is called 'class interaction' and is generalized in the notion of testability anti-pattern: it appears when potentially ...
key performance indicators; 19.On a methodology for component selection in modular branding: An industrial pilot study 机译:关于模块化品牌中组件选择的方法:一项工业试验研究 作者:Fredrik Borjesson;Robert Fancher;Ulf Sellgren 期刊名称:《Concurrent engineering》 | 2014年第2期 关键词: Branding; canniba...