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25 Cards in this Set
- Front
- Back
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What is a database?
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a collection of all files of the organization.
(the files can be stand alone or managed by a DBMS.) |
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What are two Secondary Storage Devices Classification?
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By Function: (sequential, random)
By Type: (magnetic disk, magnetic tape, optical disk) |
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What are file types by function?
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Master file
transaction file backup file history file |
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What are file access methods?
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sequential
Random access (direct access) Indexing ISAM VSAM |
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What are the procedures for Sequential (Batch) Processing?
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The Master file contains data from previous cycle. Data is stored sequentially, sorted by the record key.
2. Transactions are accumulated on a Transaction file in the random order they arrive 3. Periodically, the Transactions file is sorted by the key and merged with the Master file to create a new Master file |
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What does ISAM mean?
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Indexed Sequential Access Method
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What are the disadvantages of a file processing system?
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Duplication of Data
Limited Data Sharing Program-Data Dependence Lengthy Development Time and maintenance |
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What is data?
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all the facts, text, graphics, images, sound, and video segments that have meaning in the user environment.
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What is information?
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is data that was processed to increase the knowledge of the person who uses it.
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What is Meta data?
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are data that describes the property of other data (but doesn't include the data).
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What is a data warehouse?
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data mart) contains historical and summarized data which is used by management for decision making.
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What functions can a database application perform?
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Create, read, update, delete
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How is a database developed?
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By the conceptual and physical schema
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What is schema?
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Definition of the entire database; entities, attributes, relations.
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What is subschema?
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Portion of the schema. It defines the portion of the schema (database) which is accessible to certain users based on password.
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What is the Data Dictionary?
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(encyclopedia): holds the entire information about the database, including the tables, relations, design comments.
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What is the catalog?
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multiple schemas (Oracle terminology)
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What is DDL?
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(Data Definition Language): Used to generate the schema. It can be created via the GUI interfaces in Access or SQL commands.
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What is DML?
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(Data Manipulation Language): are the SQL commands for processing data .
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What is DBMS?
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(Database Management System): Set of programs that manages a database.
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What are the advantages of the database approach?
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Program-data independence
Minimal data redundancy Improved Data Consistency Improved Data Sharing Increased Productivity of Application Development Enforcement of Standards Improve data quality (validation, integrity checks) Improve data accessibility and responsiveness Reduce Program Maintenance Security Data recovery |
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Where are the data definitions stored?
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In the repository
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Name several different database applicaions (range)
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Personal
Department Workgroup Enterprise Internet |
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Name some of the reasons, companies/individuals have not utilized DBMS, if they are so popular.
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Cost of purchasing the database software (DBMS) is high. Depending on the system platform and number of user, it could be a six digits figure
Conversion of the old systems (referred to as legacy systems) from COBOL to SQL is expensive The usage of DBMS requires sophisticated computer professionals Organizational Conflict (politics) It required management commitment, budgets, agreements among participants |
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Name first generation DBMS.
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Hierarchical and network
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