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Lecture18

Course: COP 5725, Spring 2012
School: University of Florida
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Word Count: 724

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you What should have learned after this lecture ... what the normal forms are The following anomalies can occur: + insertion anomaly: What do we do with students who do not attend a lecture? + update anomaly: If a student reaches the next semester, we must ensure that in all tuples containing information about the student the semester number is changed accordingly. + deletion anomaly: What happens if a student...

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you What should have learned after this lecture ... what the normal forms are The following anomalies can occur: + insertion anomaly: What do we do with students who do not attend a lecture? + update anomaly: If a student reaches the next semester, we must ensure that in all tuples containing information about the student the semester number is changed accordingly. + deletion anomaly: What happens if a student drops his/her only lecture? Solution of these problems is relatively simple: decompose the relation in several subrelations which each fulfil the 2NF. Split StudentsLecture in the two relations attend(reg-id, id) and students(reg-id, name, sem). Both relations satisfy the 2NF. Moreover, they represent a lossless decomposition. remarks: no description of a decomposition algorithm which splits a given relation schema R into several 2NF relation schemas R1, ..., Rn here, because always 3NF is the goal (low importance of 2NF) violation of 2NF only with composite keys conclusion: The 2NF eliminates the partial FDs between key and non-key attributes 7.5 Third Normal Form Definition A relation schema R with associated FDs F is in third normal form (3NF), if, and only if, it is in 2NF and for each FD A B F at least one of the following conditions holds: B A, i.e., the FD A B is trivial. A is superkey of R. B is (part of) some candidate key of R. These conditions exclude non-trivial FDs between non-key attributes. That is, transitive dependencies of the type A B and B C, where A is candidate key, B is no candidate key and C contains at least one non-key attribute is forbidden. The last condition is rather unintuitive but helps to ensure that every schema has a dependency-preserving decomposition into 3NF. Example relation lecture(id, title, pers-id, room) Relation is not in 3NF because the FD pers-id room exists, and pers-id is not a key and room is not (part of) a candidate key. Possible anomalies: Information about a professor and his/her room are not available without assignment of a lecture. update anomaly: Change of the room number of a professor requires a change for each course with the same professor. deletion If anomaly: a professor does not hold a class any more, all information about the professor and his/her room is removed from the database. solution: Splitting of the schema lecture into the two schemas lecture(id, title, pers-id) and Prof(pers-id, room). conclusion: The 3NF eliminates the dependencies from non-key attributes. 3NF synthesis algorithm goal: decomposition of a relation schema R with the FDs F into relation schemas R1, ..., Rn so that the following three criteria are fulfilled: R1, ..., Rn is a lossless decomposition of R. The decomposition preserves the FDs. The schemas R1, ..., Rn each fulfil the 3NF. synthesis algorithm for computing the decomposition on the basis of F: step 1: determine a canonical cover Fc for F (i.e., left reduction of the FDs, right reduction of the remaining FDs, removal of FDs of the form A , union rule for identical left sides) step 2: for each FD A B Fc : + create a relation schema RA := A B + assign the FDs FA = {C D Fc | C D RA} to RA step 3: If all schemas RA created in step 2 do not contain a candidate key of the original schema R, additionally create a relation with the schema RK = K and FK = where K is a candidate key of R. step 4: Eliminate schemas RA that are contained in another schema RA . The result is not uniquely defined, since a set of FDs can have more than one canonical cover. In some cases the result of the algorithm depends on the order in which it considers the dependencies in Fc. Example for decomposition algorithm relation schema ProfAddr(pers-id, name, rank, room, city, street, zipcode, area-code, state, government) assumptions: A city denotes the residence of a professor. Government is the party of the president. City names are unique within a state. The zipcode does not change within a street. Cities and streets lie completely in the single states. A professor has exactly one office that he does not share. rank name pers-id room zipcode street city state areacode government {pers-id} and {room} are candidate keys of the relation ProfAddr. The relation is not in 3NF since, e.g., the FD {city, state} {area-code} violates the 3NF.
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University of Florida - COP - 5725
What you should have learned after this lecture .what the normal forms arefundamentals of database application programmingstep 1: computation of a canonical cover (precomputed) FD 1:cfw_pers-id cfw_name, rank, room, city, street, state FD 2:cfw_roo
University of Florida - COP - 5725
What you should have learned after this lecture .fundamentals of database application programmingPL/SQLexample:/ Creation of a new object of class StatementStatement stmt = con.createStatement();/ Translation of the query and creation of a new objec
University of Florida - COP - 5725
What you should have learned after this lecture . PL/SQL what data integrity means how integrity constraints are expressed in SQL PL/SQL also supports the definition of recordstype person_type is record (name varchar(50), salary int);variable declar
University of Florida - COP - 5725
What you should have learned after this lecture . How integrity constraints are expressed in QBE Why (purely) relational database systems are not sufficient any more What object-relational database systems (ORDBS) are What the benefits of ORDBS are9.
University of Florida - COP - 5725
What you should have learned after this lecture . further concepts of object-relational database systems (ORDBS) what query processing isinsert into company values(XYZ, array[Mall Avenue, Sales Street, Sellers Drive]);Alternatively:insert into compa
University of Florida - COP - 5725
What you should have learned after this lecture .how algebraic optimization is done10.2 Phases of translation/optimizationgoal: syntactical and semantical analysis of the querygiven: query in a relational query language, e.g. SQLstep 1: translation o
University of Florida - COP - 5725
What you should have learned after this lecture .how algebraic optimization is donerule 8: permutation of a selection with a join or a cross product, if it only usesattributes of one of the two operand relations. cfw_ , : F(R1 R2) = F(R1) R2(attr(F)
University of Florida - COP - 5725
10.4 Physical Optimization(We here deal only with some few aspects. This theme is especially a topic of a courseImplementation of Database Systems.)Introduction The physical algebra operators realize/implement the logical operators. A logicaloperator
University of Florida - COP - 3530
cop3530sp12Parameter passingcall by value- appropriate for small objects that should not be altered by the functioncall by constant reference- appropriate for large objects that should not bealtered by the functioncall by reference -appropriate for a
University of Florida - COP - 3530
COP 3530Data Structures &amp; AlgorithmsDiscussion Session 3OutlineInput-output streams in C+Floating point precisionFile manipulationPointers in CVector class in C+Strings in C and C+About meEyup Serdar Ayazayaz@cise.ufl.eduTA Office: E309This
University of Florida - COP - 3530
Copyright 2003 Pearson Education, Inc.Slide 1Chapter 11Strings and VectorsCreated by David Mann, North Idaho CollegeCopyright 2003 Pearson Education, Inc.Slide 2OverviewAn Array Type for Strings (11.1)The Standard string class (11.2)Vectors(11.3
University of Florida - EEL - 4712
University of Florida - EEL - 4712
University of Florida - EEL - 4712
EEL 4712Midterm 2 Spring 2011VERSION 1Name:UFID:Sign your name here if you would like for your test to be returned in class:_IMPORTANT: Please be neat and write (or draw) carefully. If we cannot read it with areasonable effort, it is assumed wron
University of Florida - EEL - 4712
EEL4712Name: Midterm1Spring2012VERSION1UFID: IMPORTANT: Please be neat and write (or draw) carefully. If we cannot read it with areasonable effort, it is assumed wrong. As always, the best answer gets the most points.COVERSHEET:Problem#: Points
University of Florida - EEL - 4712
EEL4712Name: Midterm2Spring2012VERSION1UFID: Signyournamehereifyouwouldlikeforyourtesttobereturnedinclass:_IMPORTANT: Please be neat and write (or draw) carefully. If we cannot read it with areasonable effort, it is assumed wrong. As always, the
University of Florida - EEL - 4712
University of Florida - EEL - 3396
Book sections to be covered in EEL 3396 Spring 2012 during (tentatively):Week 1: Ch 1 superficially, 2.3W2: 2.5 ,3.1.allW3: 3.2. all except 3.2.5W4: 3.3 allW5: 3.4 all, 3.5W6: 4.1, 4.2, 4.3W7: 4.4, except 4.4.5W8: 5.1 superficially, 5.2, 5.3W9: 5
University of Florida - EEL - 3396
Home work assignments in preparation for the weekly Wednesday 10 minute quizzes.Note that you can only work the quiz problem successfully if you have studied theseassignments. Quizzes will be closed book, no notes. Physical constants will be given.The
University of Florida - EEL - 3396
Home work assignments in preparation for the weekly Wednesday 10 minute quizzes.Note that you can only work the quiz problem successfully if you have studied theseassignments. Quizzes will be closed book, no notes. Physical constants will be given.Brin
University of Florida - EEL - 3396
Home work assignments in preparation for the weekly Wednesday 10 minute quizzes.Note that you can only work the quiz problem successfully if you have studied theseassignments. Quizzes will be closed book, no notes. Physical constants will be given.Brin
University of Florida - EEL - 3396
Course Number and TitleEEE 3396- Solid State Electron Devices1. Catalog Description (3 hrs) Introduction to the principles of semiconductorelectron device operation.2. Pre-requisites and Co-requisites EEL 3111 - Circuits I3. Course Objectives: To pre
University of Florida - EEL - 3396
University of Florida - EEL - 3396
University of Florida - EEL - 3396
University of Florida - EEL - 3396
University of Florida - EEL - 3396
University of Florida - EEL - 3396
University of Florida - EEL - 3396
University of Florida - EEL - 3396
University of Florida - EEL - 3396
University of Florida - EEL - 3396
Purdue - AAE - 340
Purdue - AAE - 340
C1Moment / Angular MomentumOperate on Law of Motion to obtain relationship between moment andrate of change of angular momentuma pivotal equation inrotational dynamicsDerivationiid r opvdtpiid iv pAdtLaw of Motion:F m iApOperate onthe
Purdue - AAE - 340
D1Integrals of the MotionI. Work and EnergyOperate on Law of MotioniFv m ApiipiipdvmdtiiFvpd1 imvdt 2vpivppivpkinetic energy TiiFdTvTdtpAnother form of Law ofMotionyields one scalardifferential equationIntegr
Purdue - AAE - 340
M1Rigid Bodies Angular MomentumlLaws of Motion:F M i Acmar Momentumid iH qM M qcm i AqdtqDefinitionsnM q j Fjqj 1nidqjH mjdtj 1qiqjDifficulty with applying this to systems of particles: to calculate Hrequires and d dt for every
Purdue - AAE - 340
O1Examplel ircular disk welded to a &quot;massless&quot; shaft.CShaft rotates freely in frictionless bearings at A and B.(Disk remains in a vertical plane.)Point O offset from cm by distance h.arMomentum(1)(2)(3)(4)gDerive EOMDetermine bearing react
Purdue - AAE - 340
AAE 340 Dynamics and VibrationsProblem Set 8Due: 3/9/12Problem 1: The system below consists of two particles of mass m and 2m. They areconnected by a rigid, massless rod of length L; the rod has a pivot point at C. The pivot isconstrained to move ver
Purdue - AAE - 340
AAE 340 Dynamics and VibrationsProblem Sets Format for SubmissionSubmit a professional looking document; include the following elements:1. Statement of the problem in the formGiven:Find:This is not necessarily just repeating the problem statement. R
Purdue - AAE - 340
Purdue - AAE - 340
Purdue - AAE - 340
01316 8924 1 2 7 3 449 72 6 8929 3 3 7 3 92 989 027 3 9
Purdue - AAE - 340
Purdue - AAE - 340
Purdue - AAE - 340
Purdue - AAE - 340
Purdue - AAE - 340
Purdue - AAE - 340
Purdue - AAE - 340
Purdue - AAE - 340
Purdue - AAE - 340
Purdue - AAE - 340
Purdue - AAE - 340
A1Particle KinematicsLaw of Motion :F=d( mv ) = m Adtmass constantTo use the equation, must be able to mathematically represent both sides of theequationRHSKinematics: describing motion mathematically r , v , Ar = r opv = e v oped r op= ev
Purdue - AAE - 340
B1Fundamental Vibrations ProblemgAssumptions:particle P of mass msmooth surfacelinear springviscous dampingdashpot provides force proportional to speed;always acts in direction opposing motionMotion imparted to system by external force f (t )fo
Purdue - AAE - 340
E1Example: Single Particle SystemA &quot;massless&quot; rigid rod swings in a vertical plane about a frictionlesspivot point C. At the same time, the shaft CK rotates as indicated below.A particle of mass m is attached at the end of the rod; angles and define
Purdue - AAE - 340
increase complexity of model(a/c and s/c are not really particles)System of ParticlesClassify system as comprised of particles m1, m2 , m3 ,mnClassify forces(1) Internal forces - forces between particles in the systemf jkforce exerted on particle
Purdue - AAE - 340
increase complexity of model(a/c and s/c are not really particles)System of ParticlesUseful definition : Center of MassnMRcm mj R jj 1Motion of the system : Try System FBDDerive EOMF M AicmUseful but limited - solution would producetime his
Purdue - AAE - 340
I1Systems of Particles: Integrals of the MotionI. Work and EnergyOperate on Law of MotionWhich one?F mj Aij(a)cm(b)all forces on mjF M Aiexternal forces on system(a) Single ParticleFiv m ApiipiipdvmdtiFivpvpd1 imvdt 2
Purdue - AAE - 340
Intro1IntroductionNewton's Principia (1686) is composed of threebooks:1. De motu corporum (On the motion of bodies)Volume 1 - mathematical explanation of calculus,basic dynamical definitions and implications2. De motu corporum (On the motion of bod
Purdue - AAE - 340
J1Systems of Particles: ObservationsWe have developed tools for use in analysis of problems that includemodels more complex than single particles, that is, a system that ismodeled as a general collection of n particles (no restrictions on model)For s
Purdue - AAE - 340
K1Degrees of FreedomThe number of degrees of freedom (DOF) associated with a system isequal to the number of coordinates used to describe its configurationminus the number of independent constraint equations.Note: No. of EOM = No. of DOFExample: 3 n