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30 Cards in this Set
- Front
- Back
DBMS
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Database Management System
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DML
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Data-Manipulation Language
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CLI
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Call-Level Interface
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metadata
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the schema information for the database
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PSM
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Persistent Storage Manager
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DDL
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Data Definition Language
It is part of the SQL language responsible for defining and managing all objects in a database. |
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ACID
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Atomicity: all-or-nothing execution of transations.
Consistency: constraints among data elements. Isolation: each transaction must appear to execute with no other transactions. Durability: the effect of a transaction must never be lost. |
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ODL
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Object Definition Language
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UML
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Unified Modeling Language
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DDL
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Data Definition Language
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what are are the Data Model definition and parts
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a notion for describing data or information.
1. Structure of the data 2.Operations on the data 3. Constraints on the data |
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what does the relational data model allow us to do?
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a way to represent data as a two-dimensional table called a relation.
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What is relational algebra?
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It is a formal system for manipulating relations.
* Operands are relations. * Operations include the usual set and special operations defined for relations -selection -projection -join |
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What is a Projection?
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used to produce a new relation that has some of the original attributes.
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What is a Selection?
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The selection of tuples that meet the conditions of the select statement
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What is a Join?
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The result of the natural join is the set of all combinations of tuples in R and S that are equal on their common attribute names.
Theta-Join allows for pairing of relations with multiple conditions |
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What is a Cartesian Product?
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is a result of adding the two relations together. the result is longer than the original relations because all tuples are from both relations are included in the product.
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What is an attribute?
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A column of a relation containing information specific to each tuple
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What is a schema?
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The name of a relation and the set of attributes for a relation.
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What is a tuple?
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a row containing one component for each attribute of a relation.
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What is the role of the domain of an attribute?
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To insure that each tuple component is of the proper data type. types must be atomic.
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What is an instance of a relation?
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A snapshot of the current state of the relation.
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What is the key of a relation?
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An attribute or set of attributes that are not the same for any tuple in a relation.
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What is a constraint?
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Constraints restrict the data that can be stored in relations. further restricting the domain of an attribute.
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What is a referential integrity constraint?
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Asserts that a value appearing in one context also appears in another, related context.
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What is the other name given to referential integrity constraints?
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Foreign key
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What is a superkey?
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A set of attributes that together make a key.
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What is a key?
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an attribute that functionally determines all other attributes of the relation.
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Can a key be a superkey?
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Yes
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Can a superkey be used as a primary key? Why or why not?
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Yes, the collection of attributes have no duplicated values. Therefore they can uniquely identify any tuple in the relation.
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