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Explain Record Based Logical Models?
Record-Based logical Models: Also define data at the conceptual and view levels. Unlike object-oriented models, are used to state overall logical structure of the database, and gives a higher-level description of the implementation. Named so since the database is structured in fixed-format records of various types. Each record type defines a fixed number of fields, or attributes. Each field is commonly of a fixed length (this simplifies the implementation). Record-based models do not involved a mechanism for direct representation of code in the database. Separate languages related along with the model are used to express database queries and updates. The three most widely-accepted models are the relational, network, and hierarchical.
How is concurrency identified? Concurrency in objects can be identified by the way they alter their state. Current objects can change their state independently. Aggregation imp
Define null values. In some cases a certain entity may not have an applicable value for an attribute or if we do not know the value of an attribute for a certain entity. In the
Explain what is DDL? DDL - Data Definition Language: statements used to define the database structure or schema. Some examples: CREATE - to create objects in the database ALT
Describe an data dictionary? A data dictionary is a data structure which keeps meta data about the structure of the database ie. the schema of the database.
Differentiate between B-tree and B + tree Ans: A B-tree (or Balanced Tree) is a search tree along with additional constraints that makes sure that the tree is all the time
4. Describe three ways to handle missing field values
Represent the following scenarios with E-R diagrams drawn using the ER Assistant software. The diagrams should indicate cardinality and optionality of relationships. Transform each
Explain about database system structure? Storage manager Authorization and integrity manager Transaction manager File manager Buffer manager Storage manager
cardnality ratio for humanresource mangement system
what factors might influence a company to outsource its IT infrascture.
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