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31 Cards in this Set
- Front
- Back
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Database (DB)
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Integrated collection of data and metadata
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Metadata
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Data that describes other data
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Database Management System (DBMS)
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Application or system software that stores and provides access to data stored in one or more databases
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Data Integration
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Modern organizations store and use petabytes (1015 bytes) of data.
Data relates to all aspects of the organization – accounting and financial, customers, suppliers, inventory, products, production processes, competitors, R&D, … Data are related to other data in many ways An efficient and effective information system automatically recognizes and uses the “connections” among data |
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Data Integration examples
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An order to Dell for a laptop is based on a product catalog, generates a production order, generates orders for parts, and schedules assembly and testing
Shipment/delivery of the laptop decreases inventory and results in cash inflow that’s recorded in the customer account and eventually the financial statements. Changing an order before it enters production affects production, inventory, ordering, future cash flow, and possibly incentives to employees based on sales or profits To UNM, Stephen Burd is an employee, instructor, faculty member, vendor, and student Despite Burd’s multiple roles within the organization, most descriptive data about him should be stored only once Certain database updates are allowed for Burd that might not be allowed for other persons – for example, it should be impossible for a student who isn’t also an instructor or faculty member to assign a grade in a course. |
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Database (DB)
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Integrated collection of data and metadata.
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Integration implies that..
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relationships among data items such as names, addresses, course titles, and grades are recognized and stored within the system
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Examples of Integration
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A particular paycheck was deposited to Burd’s checking account
Burd enrolls in a particular course during a particular semester and receives a grade for that course The course Burd completed satisfies one requirement of a particular degree program Burd teaches a particular course and assigns grades to all students enrolled in that course |
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Metadata
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Data that describes other data
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types of metadata
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Single and multiple data item value constraints
Data naming and organization Computation of derived values Security Location |
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Single and multiple data item value constraints examples
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Salary must be a positive number
Allowable grades are A, B, C, … If grade is A then points earned is 4.0 If student status is “suspended” then currently enrolled credits must be zero. |
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Data naming and organization
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for example, the data item Name is part of the Person table and is indexed alphabetically to speed alphabetic searches.
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Computation of derived values example
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how is grade point average computed from grades earned
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Security
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What users can view, change, or delete grades and salaries?
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Location
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Where is a particular group of data items stored (on what disk and machine)? If they’re stored in multiple places, which holds the “original” or “master” and which are the copies?
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Database Management System (DBMS)
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Application or system software that stores and provides access to data stored in one or more databases
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Application software
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solves a very particular problem. Eg a game.
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Database Management Systems (DBMSs) MUST HAVE
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Must support storage of data items, relationships among data items, and metadata
Must be capable of managing multiple database – for example, one for production and another for accounting Must be flexible enough to support many kinds of data and databases (many different application areas). Must provide access to the data, preferably via a variety of paths such as: Direct access for end users via interactive tools Access via report generation tools Access from application programs written in multiple languages (e.g., Java, Visual Basic, and Web scripts) executing locally and remotely Must enable concurrent access by many users and applications |
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Key Database and DBMS Benefits
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Data are more easily shared across application programmers, users, and parts of an organization
Data are managed as an organizational resource Cost-efficiency Security and privacy Data as an asset Application software is independent of many aspects of data storage, especially physical ones Data quality can be enforced consistently across applications throughout the organization Many changes to the database have no effect on existing programs Data can be accessed without writing programs |
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Database/DBMS - Prehistory - before 1965:
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Data are stored in computerized files.
Files contain records and records contain fields (numbers, characters, and strings) Computerized files are created for specific application programs and groups of application programs (for example, student grades, payroll, accounts payable) Connections among files across application areas are weak or nonexistent (for example, Burd’s student, employee, and vendor ID numbers have different values and formats) Redundancy among files is high (for example, Burd’s address is stored in three different files which must all be updated if he moves). |
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Database/DBMS History – First Era 1965 - 1980
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CODASYL Committee defines a standard commonly called “network databases”
Common data type definitions Relationships represented using pointers Common access methods Several mainframe products are matched to the standard – IMS and IDMS become the dominant DBMSs Rapid computerization of business processes fuels demand for DBMSs – Most business applications use them by the early 1980s. |
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Database/DBMS History – Second Era 1975 - Present
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Relational database standard is developed in the early 1970s.
Commercial relational DBMS products appear in late 1970s, many based on experimental software developed on UNIX running on minicomputers Relational DBMSs gradually supplant CODASYL DBMSs throughout the 1980s Database explosion continues – fueled by increasing automation levels, ever cheaper computers and disk storage, and ever more data-intensive business practices. |
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Database/DBMS History – Third Era - 1995 - Present
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Databases are ubiquitous
PCs, mainframes, supercomputers, business, science, government, … Large organizations have hundreds to tens of thousands of databases – integration across DBs is the big problem Terabyte and petabyte databases become commonplace Data is accessed globally from inside and outside the organization (supply chain integration, direct customer interaction, …) – ubiquitous networks, the Web, and related standards make this possible Relational DBMSs change little while software evolves from structured to object-oriented tools and languages and from machine-centered applications to distributed and Web-based applications |
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Database/DBMS Current Issues/Problems
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Organizations are overwhelmed by the volume of data
Data has value independent of its support for “ordinary” business processing (e.g., marketing analysis for trends and new products) Modern software views data and software as an integrated whole (the object-oriented view) but relational DBMSs treat them separately Relational DBMSs are a poor fit to modern software and applications – limiting the kinds of data that can be stored and the types of applications that can be feasibly built and maintained (e.g., genome analysis and genetically-customized drug design and production using a relational database?) The sheer volume of data stored in relational databases and the dependence of “everything” on those databases and their host DBMSs makes change almost unthinkable. |
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What is a DBMS?
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DBMSs can be small-scale (e.g., Microsoft Access) or large-scale (e.g., Oracle).
For medium- and large-scale applications, a DBMS is a large, complex, and expensive program |
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Characteristics of a DMBS
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Tightly bound to the operating system since both share responsibility for accessing disk storage, network I/O, and control of related hardware resources.
Resource-hungry – industrial strength DBMSs require industrial-strength hardware costing thousands to tens of millions of dollars. Difficult to manage – requires an army of highly-trained specialists. |
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Some DBMS Products
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Desktop
Access (Jet) FoxPro Paradox Enterprise Oracle SQL Open Source: mySQL, PostgreSQL, Firebird Embedded SQL Server Mobile Open Source |
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Who Creates/Manages Your Database?
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End User
Analyst/Programmer Data Administrator Database Administrator (DBA) |
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Analyst/Programmer
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Gathers user requirements
Designs applications Implements information systems Knowledge of procedural & nonprocedual |
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Data Administrator
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Plans database development
Establishes standards for databases |
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Database Administrator (DBA)
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Database design/development
Plans, creates & maintains database Knowledge of procedural & nonprocedual |
