REVISED: Sunday, March 3, 2013
You will receive an introduction to databases.
I. INTRODUCTION TO DATABASES
A database is a set of named relations or tables. Each relation has a set of named attributes or columns. Each tupple or row has a value for each attribute. Each attribute has a type or domain.
A. TERMINOLOGY
1. Schema
Schema is the structural description of the relations in a database.
Instance is the actual contents of a database at a given point in time.
Relations are tables.
4. Attributes
Attributes are columns.
5. Tuples
Tuples are rows.
6. Types
Types are domains.
7. Null
Null is a special value for unknown or undefined.
Key is a unique attribute in each tuple or set of attributes whose combined values are unique.
Ad-hoc queries are questions you did not think of in advance.
Queries return relations.
11. Compositionality
Compositionality is the ability to run a query over the results of a previous query.
Query languages include SQL and Relational Algebra.
XML is the Extensible Markup Language (XML) was designed originally for exchanging data on the Internet. XML basic construct consists of nested tagged elements, attributes, and text. Data can be stored in relational databases or XML. A parser can be used to determine if the XML is well formed.
a. Single root elements.
b. Properly nested matched tags.
c. Unique attributes within elements.
Parsed XML can be accessed by Document Object Model (DOM) and in streams by SAX.
Rule based languages such as Cascading Style Sheets (CSS) and Extensible Stylesheet Language (XSL) can be used to display XML as HTML.
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How to Link to My Home Page
It will appear on your website as:"Link to ELCRIC OTTO CIRCLE's Home Page"
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