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Data management comprises all the disciplines related to managing data as a valuable resource. The official definition provided by DAMA is that "Data Resource Management is the development and execution of architectures, policies, practices and procedures that properly manage the full data lifecycle needs of an enterprise." This definition is fairly broad and encompasses a number of professions which may not have direct technical contact with lower-level aspects of data management, such as relational database management.
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The entity-relationship model or entity-relationship diagram (ERD) is a data model or diagram for high-level descriptions of conceptual data models, and it provides a graphical notation for representing such data models in the form of entity-relationship diagrams. Such models are typically used in the first stage of information-system design; they are used, for example, to describe information needs and/or the type of information that is to be stored in the database during the requirements analysis. The data modelling technique, however, can be used to describe any ontology (i.e. an overview and classifications of used terms and their relationships) for a certain universe of discourse (i.e. area of interest). In the case of the design of an information system that is based on a database, the conceptual data model is, at a later stage (usually called logical design), mapped to a logical data model, such as the relational model; this in turn is mapped to a physical model during physical design. Note that sometimes, both of these phases are referred to as "physical design".
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There are a number of conventions for entity-relationship diagrams (ERDs). The classical notation is described in the remainder of this article, and mainly relates to conceptual modelling. There are a range of notations more typically employed in logical and physical database design, including information engineering, IDEF1x (ICAM DEFinition Language) and dimensional modelling
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The designer of a database builds a formal model of the application area or universe of discourse (UoD). The model requires a good understanding of the UoD and a means of specifying this understanding in a clear, unambiguous way. Object Role Modeling (ORM) simplifies the design process by using natural language, as well as intuitive diagrams which can be populated with examples, and by examining the information in terms of simple or elementary facts. By expressing the model in terms of natural concepts, like objects and roles, it provides a conceptual approach to modeling.
Early versions of object role modeling were developed in Europe in the mid-1970s (for example, binary relationship modeling and Nijssen's Information Analysis Method (NIAM)).
The best book on ORM is "Information Modeling and Relational Databases" written by Terry Halpin.
Microsoft has a powerful implementation of ORM embedded within the product "Microsoft Visio for Enterprise Architects." With this tool you can quickly design and build database in fifth normal form. You can also reverse engineer one or more databases into natural language and then check their semantic accuracy with domain experts. Microsoft chose not to prepare a "how to" manual for ORM. Instead, Microsoft supported ORM experts who wrote the book "Database Modeling with Microsoft Visio for Enterprise Architects." So if you want to this powerful Microsoft ORM tool, it will help if you buy this book.
2005 In Review, A Glimpse Back
Disasters, Big and Small - Hurricane Katrina
Katrina first made landfall as a Category 1 hurricane just
north of Miami, Florida in late August, resulting in a dozen
deaths in South Florida and spawning several tornadoes which
happened not to strike any dwellings. In the Gulf of Mexico it
strengthened into a formidable Category 5 hurricane with maximum
winds of 175 mph and minimum central pressure of 902 mbar. It
weakened considerably as it was approaching land, making its
second landfall on the morning of August 29 along the Central
Gulf Coast near Buras-Triumph, Louisiana with 125 mph winds and
a central pressure of 920 mbar, a strong Category 3 storm
(having just weakened from Category 4 as it was making
landfall).
The sheer physical size of Katrina caused devastation far
from the eye of the hurricane; it was possibly the largest
hurricane of its strength ever recorded, but estimating the size
of storms from before the 1960s (the pre-satellite era) is
difficult or impossible. On August 29, its storm surge breached
the levee system that protected New Orleans from Lake
Pontchartrain and the Mississippi River. Most of the city was
subsequently flooded mainly by water from the lake. Heavy damage
was also inflicted onto the coasts of Mississippi and Alabama,
making Katrina the most destructive and costliest natural
disaster in the history of the United States and the deadliest
since the 1928 Okeechobee Hurricane.
Iraqi Quagmire
Under the Iraqi constitution of 1925, Iraq was a
constitutional monarchy, with a bicameral legislature consisting
of an elected House of Representatives and an appointed Senate.
The lower house was elected every four years by manhood suffrage
(that is, women did not vote). The first Parliament met in 1925.
Ten general elections were held before the overthrow of the
monarchy in 1958. The electoral system, however, was manipulated
by the King and his advisors, who were Sunni Muslims, to ensure
that the Shi'a majority were prevented from taking power.
Between 1958 and 2003 Iraq was ruled by a series of military
regimes, all dominated by members of the Sunni Arab minority.
Both the Shi'a and the Kurds were excluded from power, and under
the regime of Saddam Hussein, who came to power in 1979, they
were persecuted. Saddam's regime was largely run by Sunni Arabs
from Tikrit, his home region. On October 16, 2002, after a
well-publicized show election, Iraqi officials declared that
Saddam had been re-elected to another seven-year term as
President by a 100% unanimous vote of all 11,445,638 eligible
Iraqis, eclipsing the 99.96% received in 1995. The United States
and others outside Iraq said the vote lacked any credibility.
Stories later surfaced stating that voting was compulsory and
that the "yes" box had already been checked for voters in
advance.
The multinational force's invasion of Iraq in 2003 overthrew
Saddam's regime and installed an interim government in which all
Iraq's ethnic and religious communities were represented. This
government held elections on January 30, 2005 to begin the
process of writing a constitution. Pro-U.S. groups and the
formerly excluded Shi'a and Kurd factions claimed that the
January 2005 elections were the first genuine free elections in
Iraq's history, or at least since the 1950s. Opponents of the
occupation, such as the insurgents and the Sunni faction, claim
that the elections were not genuinely free and fair, pointing to
several flaws in the process.
Loss of a Father, Pope John Paul II's Death
The funeral of Pope John Paul II was held on 8 April 2005,
six days after his death on 2 April. The funeral was followed by
the novemdiales devotional in which the Roman Catholic Church
and its Eastern Rite observe nine days of mourning.
On February 22, 1996, Pope John Paul II introduced revisions
to the centuries-old ceremonies surrounding papal death, repose
and burial. The revisions enacted through the apostolic
constitution Universi Dominici Gregis applied to his own
funeral.
Coinciding with the funeral in Vatican City, archbishops and
bishops at cathedrals throughout the world celebrated memorial
masses for grieving Roman Catholics.
In a historical rarity, Protestant and Eastern Orthodox
Christian leaders, as well as leaders in Judaism and Islam,
offered memorials and prayers of their own for their congregants
sharing in the grief of Roman Catholics. The current Archbishop
of Canterbury was present at the papal funeral for the first
time since the Church of England broke with the papacy in the
16th century.
London Terror, Bombings
The 7 July 2005 London bombings were a series of co-ordinated
suicide bombings that struck London's public transport system
during the morning rush hour. The bombings killed 52 civilians
and injured over 700 people.
At 8:50 a.m. (BST, UTC+1), three bombs exploded within 50
seconds of each other on three London Underground trains. A
fourth bomb exploded on a bus at 9:47 a.m. in Tavistock Square.
The bombings led to a severe, day-long disruption of the city's
transport and mobile telecommunications infrastructure.
Fifty-six people were killed in the attacks, including the
four suspected bombers, with 700 injured. The incident was the
deadliest single act of terrorism in the United Kingdom since
the 1988 bombing of Pan Am Flight 103 (which killed 270), and
the deadliest bombing in London since the Second World War.
Police investigators identified four men whom they believed to
be suicide bombers. These are the first suicide bombings in
Western Europe, and are thought to have been planned by Islamist
paramilitary organizations based in the United Kingdom; the
terrorist organization al-Qaeda claimed responsibility.
The bombings came while the UK was hosting the first full day
of the 31st G8 summit, a day after London was chosen to host the
2012 Summer Olympics, two days after the beginning of the trial
of fundamentalist cleric Abu Hamza, five days after the Live 8
concert was held there, and shortly after Britain had assumed
the rotating presidency of the Council of the European Union.
On 21 July 2005, a second series of four explosions took place
on the London Underground and a London bus. However, this time
only the detonators of the bombs exploded, and all four bombs
remained undetonated. There were no fatalities: the single
injury reported at the time was later revealed to be a
hospitalized asthma sufferer. All suspected bombers from this
failed attack have been arrested by police.
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