• Entity
    An entity set that does not possess sufficient attributes to form a primary key is called a weak entity set. One that does have a primary key is called a strong entity set. For example, The entity set transaction has attributes transaction-number, date and amount. Different transactions on...
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  • Er Model
    set is formed by the primary key of the strong entity set on which the weak entity set is existence dependent, plus the weak entity set’s discriminator. 12 Textbook: Database System Concepts 5th Edition, 2005 INFSCI1022 6 Weak Entity Sets (Cont.)  We depict a weak entity set by double...
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  • Er Diagram
    Sudarshan c 1997  ' & Weak Entity Sets $ • An entity set that does not have a primary key is referred to as a weak entity set. • The existence of a weak entity set depends on the existence of a strong entity set; it must relate to the strong set via a one-to-many relationship set. • The...
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  • Dbms
    previous question to track the same information for all teams in a league. Answer: See Figure 2.7 Note that a player can stay in only one team during a season. 2.9 Explain the difference between a weak and a strong entity set. Answer: A strong entity set has a primary key. All tuples in the set are...
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  • Database Systems
    The entity-relationship model (or ER model) is a way of graphically representing the logical relationships of entities (or objects) in order to create a database. entity type is a collection of entity instances sharing similar properties Strong Entity Vs Weak Entity An entity set that does not...
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  • Er Model
    during a season. 2.9 Explain the difference between a weak and a strong entity set. Answer: A strong entity set has a primary key. All tuples in the set are distinguishable by that key. A weak entity set has no primary key unless attributes of the strong entity set on which it depends are included...
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  • Database Management System
    ) Normalizing the relations. Once ER / EER model has been developed for the application , ER/ EER diagram can be mapped into a relational model . ER/ EER diagram consists of the following components. 1) Entities (Strong , Weak) with attributes 2) Attributes may be Single, Simple, composite or...
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  • Huffman Trucking Entity-Relationship Model
    Entities Existence dependency: Entity Y is existence dependent on entity X is each instance of Y must have a corresponding instance of X In that case, Y must have total participation in its relationship with X If Y does not have its own candidate key, Y is called a weak entity, and X is strong entity...
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  • Hello
    2914 ERD: Relationships Ron McFadyen Identifying Relationships An Identifying Relationship is a relationship between a strong and a weak entity type, where the key of the strong entity type is required to uniquely identify instances of the weak entity type. The weak entity type will have a...
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  • Erd Model
    Entities – Relationships – Attributes Entity Type • Entity - distinguishable “thing” in the real world – Strong (or regular) entity - entities have an independent existence (e.g. staff) – Weak entity - existence dependent on some other...
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  • Databasemanagementsystems
    weak entity set. An entity set that has a primary key is termed a strong entity set. [pic] For a weak entity set to be meaningful, it must be associated with another entityset, called the identifying or owner entity set. Every weak entity must be associated with an identifying entity; that is...
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  • Database Management Intro
    entities. Entities whose existence not depending on any other entities is termed as existence independent. STRONG AND WEAK RELATIONSHIP An entity set that has a primary key is named as strong entity set. An entity set that does not have enough attributes to form a primary key is named as a weak...
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  • E-R Diagram
    CUSTOMER table .To do this,we will place a foreign key in the ORDERS table and have it related to the primary key of the CUSTOMER table. Strong and Weak Entities:- * An entity set may not have sufficient attributes to form a primary key. Such an entity set is termed a weak entity set. An entity...
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  • world champ
    that would be identified by the entity. Further, the definition of weak or strong entity would depend on the identifying information that was to be provided. Figure 6.10: An ER Diagram of the COURSE–INSTRUCTOR Database Finally, if no information about instructors were ever planned, then the first...
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  • Chapter 4 -SQL
    integrity errors, regardless of whether the relationships are weak or strong. A weak entity as one that meets two conditions: 1. The entity is existence-dependent; that is, it cannot exist without the entity with which it has a relationship. 2. The entity has a primary key that is partially or...
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  • Economics
    Map Binary Relationships Map Weak Entities Map Associati e Entities Associative Map Unary Relationships Map Ternary (and n-ary) Relationships 57 3. Mapping Weak Entities pp g • A weak entity becomes a separate relation with a foreign key taken from the strong entity • Primary key...
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  • Site Recommendations
    . Following are the classification of the entities types 1. Strong Entities: An entity having a primary key is called as strng entity. For e.g. EMPLOYEE entity identified by employee id as primary key. 2. Weak Entities An entity that do not have a primary key is termed as weak entitiy and they are...
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  • Entity Relational Diagram
    prerequisite Course course Role Names Prof P Sreenivasa Kumar Department of CS&E, IITM 24 prereqOf Weak Entity Sets Weak Entity Set: An entity set whose members owe their existence to some entity in a strong entity set. entities are not of independent existence. each weak entity is associated...
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  • question answer
    12.8 Describe how strong and weak entity types differ and provide an example of each. A strong entity type is an entity type that is not existence-dependent on some other entity type A weak entity type is an entity type that is existence-dependent on some other entity type...
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  • Entity-Relationship Diagrams and the Relational Model
    said to be total (vs. partial) – What if every department has an employee working in it? Weak Entities A weak entity can be identified uniquely only by considering the primary key of another (owner) entity. – Owner entity set and weak entity set must participate in a one-to-many relationship set...
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