Windows Programming .NET Overview
What is a Computer? From the Websters New World Dictionary: 1. A person who computes. 2. A device used for computing (an electronic machine which by means of stored instructions and information, perform rapid
Introduction to SQL
Select-From-Where Statements Multirelation Queries Subqueries
SQL is a very-high-level language.
Say "what to do" rather than "how to do it." Avoid a lot of data-manipulation details needed in procedural languages like C+ o
Extended Relational Algebra Outerjoins, Grouping/Aggregation Insert/Delete/Update
The Extended Algebra
= eliminate duplicates from bags. = sort tuples. = grouping and aggregation.
Outerjoin : avoids "dangling tuples" = tuples
that do not join
Basic Operations Algebra of Bags
What is an "Algebra"
Mathematical system consisting of:
Operands - variables or values from which new values can be constructed. Operators - symbols denoting procedures that construct new values from
Design Theory for Relational Databases
Functional Dependencies Decompositions Normal Forms
x X >Y is an assertion about a relation R that whenever two tuples of R agree on all the attributes of X, then they must also agree on all
Logical Rules Recursion
Logic As a Query Language
x Ifthen logical rules have been used in many systems. x Nonrecursive rules are equivalent to the core relational algebra. x Recursive rules extend relational algebra and appear in SQL99.
Foreign Keys Local and Global Constraints Triggers
Constraints and Triggers
A constraint is a relationship among data elements that the DBMS is required to enforce.
Example: key constraints.
Triggers are only executed when a specified condi
x WellFormedXMLallowsyoutoinvent yourowntags. x ValidXMLconformstoacertainDTD.
x Startthedocumentwithadeclaration, surroundedby<?xml?>. x Normaldeclarationis: <?xml version = 1.
x Standardsgroup:ODMG=ObjectData ManagementGroup. x ODL=ObjectDescriptionLanguage, likeCREATETABLEpartofSQL. x OQL=ObjectQueryLanguage,triesto imitateSQ
CallLevelInterface JavaDatabaseConnectivity PHP
x SQLqueriesareoftenconstructedby programs. x Thesequeriesmaytakeconstantsfrom userinput. x Carelesscodecanallowrather unexpectedqueriestobeconstructed and
Privileges GrantandRevoke GrantDiagrams
x Afilesystemidentifiescertainprivileges ontheobjects(files)itmanages. x Afilesystemidentifiescertain participantstowhomprivilegesmaybe granted.