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27 Cards in this Set
- Front
- Back
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How many components does a data base system have and what are they?
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4
Users, database application, dbms, and database |
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Database
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A collection of related tables and other structures
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DBMS
Database Management system |
a computer program used to create, process, and administer the database
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Database application
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a set of one or more computer programs that serves as an intermediary between the user and the DMBS
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Users
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employ a database application to keep track of things.
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A database is self-describing collection of related tables. Define the two terms.
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Self-describing: a description of the structure of the database is contained within the database itself
related tables: I.e (adviser and student) relate to eachother |
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Metadata
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data about the structure of a database
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Functions of a DBMS
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create database, create tables, create supporting structures, read database data, modify(insert, update, or delete) database data, maintain database structures, enforce rules, control concurrency, provide security, preform backup and recover
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Referential integrity constraint
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rules the DBMS enforces (find notes to elaborate more)
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concurrency
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controlled by ensuring that one users work does not inappropriately interfere with another user's work.
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Functions of database application programs
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create and process forms, process user quieries, create and process reports, execute application logic, control application
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what are the three type of modification problems(actions)
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insert, delete, change(update)
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Entity
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the formal name for a "thing" that is being tracked. Defined as something of importance to the user that needs to be represented in the database.
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Relation
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special type of two dimensional table consisting of rows and columns
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What is the equivalent term for a table?
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File or Relation
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What is the equivalent term for a row?
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Record or Tuple
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What is the equivalent term for a column?
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Field, Attribute
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Composite Key
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a key that contains two or more attributes
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Candidate key
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keys that uniquely identify each row in a relation. Candidate to becoming the primary key
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Primary Key
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the canidate key that is chosen as the key that the DBMS will use to uniquely identify each row in a relation
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Surrogate Key
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a column with a unique DBMS-assigned identifier that has been added to a table to be the primary key.
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Surrogate Key T or F
1. the values change |
False
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Foreign Key
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The primary key values used in the first relation becomes an attribute in the second relation with the same value
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Null value
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missing value in a cell in a relation.
No value is appropriate, the value is known to be blank, the value is simply unknown |
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What is the functionally dependent and what is the determinant in:
Cookiecost= NumberofBoxes x 5 |
dependent is cookie cost
determinant is numberofboxes |
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NumberOfBoxes---->CookieCost
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The numberofboxes determines cookiecost
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(Quantity, UnitPrice) ---> ExtendedPrice
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the composite quantity and unit price is the determinant of extendedprice
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