File and database concepts
In the broadest definition, a database is a collection of data. Today, databases are typically stored as computer files. The tasks associated with creating, maintaining, and accessing the information in these files are referred to as data management, file management, or database management. The basic element of a structured file is a field. It contains the smallest unit of meaningful information. Each field has a unique field name that describes its contents. For example, in the Vintage Music Shop database, the field name Album Title describes a field containing the name of an album, such as Hard Day’s Night. A field can be variable length or fixed length. A variable-length field is like an accordion – it expands to fit the data you enter, up to some maximum number of characters. A fixed-length field contains a predetermined number of characters (bytes). The data you enter in a fixed-length field cannot exceed the allocated field length. Moreover, if the data you enter is shorter than the allocated length, blank spaces are automatically added to fill the field.
In the world of computing, a record refers to a collection of data fields. Computer databases typically display records as rows in a table or as forms. Each kind of record is referred to as a record type. It is usually shown without any data in the fields. A record that contains data is referred to as a record occurrence, or simply a record.
A structure file that contains only one record type is often referred to as a flat file. Flat files can be used to store simple data, such as names and addresses. In contrast, a database can contain a variety of different record types. A key characteristic of a database is its ability to maintain relationships so that data from several record types can be consolidated or aggregated into essentially one unit for data retrieval and reporting purposes. In database jargon, a relationship is an association between data that’s stored in different record types. For example, Vintage Music Shop’s Customers record type is related to the Orders record type because customers place orders.
An important aspect of the relationship between record types is cardinality. Cardinality refers to the number of associations that can exist between two record types. When one record is related to many records, the relationship is referred to as a one-to-many relationship. A many-to-many relationship means that one record in a particular record type can be related to many records in another record type, and vice versa. The relationship between record types can be depicted graphically with an entity-relationship diagram (sometimes called an “ER diagram” or “ERD”).
Several database models exist. Some models work with all the relationships described earlier in this section, whereas other models work with only a subset of the relationships. The four main types of database models in use today are hierarchical, network, relational, and object oriented. The simplest database model arranges record types as a hierarchy. In a hierarchical database, a record type is referred to as a node or “segment”. The top node of the hierarchy is referred to as the root node. Nodes are arranged in a hierarchical structure as a sort of upside-down tree. A parent node can have more than one child node. But a child node can have only one parent node.
The network database model allows many-to-many relationships in addition to one-to-many relationships. Related record types are referred to as a network set, or simply a “set”. A set contains an owner and members. An owner is similar to a parent record in a hierarchical database. A member is roughly equivalent to a child record. The most popular database model today is a relational database model. It stores data in a collection of related tables. Each table (also called a “relation”) is a sequence, or list, of records. All the records in a table are of the same record type. Each row of a table is equivalent to a record and is sometimes called a tuple. Each column of the table is equivalent to a field, sometimes called an attribute. Relationships can be added, changed, or deleted on demand. An object-oriented database stores data as objects, which can be grouped into classes and defined by attributes and methods. A class defines a group of objects by specifying the attributes and methods these objects share. The attributes for an object are equivalent to fields in a relational database. A method is any behavior that an object is capable of performing. There is no equivalent to a method in a non-object-oriented database.
Comprehension check. Mark the following statements as True or False.
1. The field is a basic element of a structured file.
2. The field contains the biggest unit of meaningful information.
3. The length of a field is always fixed.
4. Simple data, such as names and addresses, can be stored in flat files.
5. Every relation is a sequence, or list, of records.
6. Relationships can be changed or deleted on demand.
Vocabulary practice
1. In the text, find the synonyms to the given words.
a node important several typically to perform to comprise
2. Fill in the blanks choosing from the variants given.
1. The most popular database model today is a … database.
a) relational b) object-oriented c) non-object
2. The data you enter in a … field cannot exceed the allocated field length.
a) fixed-length b) variable-length
3. All the records in a table are of the same record … .
a) group b) type c) set
4. The simplest database model arranges record types as a … .
a) hierarchy b) column c) relation
5. Each field has a … field name that describes its contents.
a) unique b) unusual c) unknown
6. All the records in a table are of the … record type.
a) same b) different c) simple
3. Make two-word combinations using the words in columns and then fill in the gaps in the following sentences.
A: a) non-object-oriented B: type
b) a many-to- many relationship
c) record database
d) flat length
e) simple data
f) allocated file
1. Any kind of record is referred to as a … .
2. Flat files can be used to store …, such as names and addresses.
3. Moreover, if the data you enter is shorter than the …, blank spaces are automatically added to fill the field.
4. There is no equivalent to a method in a … .
5. A structure file that contains only one record type is often referred to as a … .
6. … means that one record in a particular record type can be related to many records in another record type, or vice versa.
4. Fill in the gaps in the text.
Computer databases evolved from manual file processing technology in which data is stored in a single _1_ file that uses a uniform format for every item the file contains. A _2_ holds the smallest unit of meaningful information. A series of data fields forms a _3_, which stores data about one entity – a person, place, thing, or event.
Each kind of record is referred to as a record type. A record that contains data is sometimes referred to as a record _4_. A _5_ file contains only one record type. In contrast, a _6_ can contain a variety of different record types.
Speaking. Discuss the following questions.
1. What is a database?
2. What is the basic element of a structured file?
3. What is a record?
4. What is involved in defining the structure for records in a file?
5. What are relationships?
Text B
Reading. Read the text and try to guess the meaning of the words in bold. Check your variants in the dictionary.
DATA MANAGEMENT TOOLS
Data Management Software
The simplest tools for managing data are software packages dedicated to a specific data management task, such as keeping track of appointments or managing your checking account. You can purchase these tools or download them from Internet. Although these tools are easy to use, they don’t generally allow you to create new record types because the record types are predefined. Most spreadsheet and word processing software packages feature simple tools that allow you to specify fields, enter data and manipulate it. For example, Microsoft Excel allows you to sort records, validate data, search for records, perform simple statistical functions, and generate graphs based on the data. Such simple file management tools are popular for individuals who want to maintain flat files that contain hundreds, not thousands, of records. To create your own data management software it is possible to simply enter data as an ASCII text file, and then use a programming language to write routines to access that data. Modern database software supports data independence, which means separating data from the programs that manipulate data. As a result, a single data management tool can be used to maintain many different files and databases.
Database Management Systems
The term DBMS (Database Management System) refers to software that is designed to manage data stored in a database. Each DBMS typically specializes in one of the four database models, but some DBMS software offers versatility by dealing with a variety of models and data. An XML DBMS, for example, is optimized for handling data that exists in XML format. An OODBMS (object-oriented database management system) is optimized for the object-oriented database model, allowing you to store and manipulate data classes, attributes, and methods. Database client software allows any remote computer or network workstation to access data in a database.
Databases and the Web
The Web provides an opportunity for many people to gain access to data from multiple locations. The simplest way to provide Web access to database is converting a data base report into an HTML document, which can be displayed as a Web page by a browser. This technique is called static Web publishing. Web access is constrained by the stateless nature of HTTP. In several situations, such as e-commerce, it is important for people to use a browser to add or update records in a database. For example, the process of ordering merchandise at Vintage Music Shop creates a new order record, changes the InStock field in the Albums table, and creates a customer record for first-time customers. These dynamic database updates require an architecture similar to that used for dynamic Web publishing, plus the use of forms. A form usually exists on a Web server, which sends the form to your browser. Several tools, including ASP, CGI, and PHP, help you create server-side programs on which dynamic Web publishing relies.
XML Documents
XML is a markup language that allows field tags, data, and tables to be incorporated into a Web document. It was developed in response to several deficiencies that became apparent as HTML gained widespread use. For example, suppose you are interested in speeches given by Martin Luther King, Jr. Entering his name in a search engine produces thousands of entries, including MLK biographies, streets and schools named after the famous civil rights leader, historic locations relating to the civil rights movement and so on. XML provides tags that can be embedded in an XML document to put data in context.
As you can see, many techniques exist for storing, accessing, and displaying the data from the databases. Sometimes more than one tool has the potential to work for a specific application. Now that you’ve had an introduction to the options, you should be able to evaluate when and how to use them.
Comprehension check. Mark the following statements as True or False.
1. Many techniques exist for storing, accessing, and displaying the data from the databases.
2. The Web provides an opportunity for a limited number of people to gain access to data from multiple locations.
3. Simple file management tools are popular for individuals who want to maintain files that contain thousands of records.
4. The term DBMS (Database Management System) refers to software that is designed to manage data stored in a database.
5. Microsoft Excel doesn’t allow you to sort records, validate data, search for records, perform simple statistical functions, and generate graphs based on the data.
6. XML is a markup language that allows field tags, data, and tables to be incorporated into a Web document.
Vocabulary practice
1. In the text find the opposites to the given words.
civil sometimes simple purchase allow unknown
2. Fill in the blanks choosing from the variants given.
1. Most spreadsheet and word processing software (sets, packages, collections) feature simple tool that allow you to specify fields, enter data and manipulate it.
2. As you can see, many techniques (are existing, exist, have been existed) for storing, accessing, and displaying the data from the databases.
3. For example, Microsoft Excel (to allow, is allowing, allows) you to sort records, validate data, search for records.
4. XML (were, is, have been) a markup language that allows field tags, data, and tables to be incorporated into a Web document.
5. Now that you (have had, had, has had) an introduction to the options, you should be able to evaluate when and how to use them.
6. Many (methods, ways, techniques) exist for storing, accessing and displaying the data from the databases.
3. Make three-word combinations using the words in the columns and then fill in the gaps in the following sentences.
A: a) address B: client C: software
b) system management task
c) database book database
d) data management system
e) database management information
f) data server software
1. The simplest tools for managing data are soft packages dedicated to a specific … .
2. The term DBMS … refers to software that is designed to manage data stored in a database.
3. Simple tools that easily store … might not be suited for managing a worldwide airline reservation system.
4. To create your own … it is possible to simply enter data as an ASCII text file.
5. … is designed to manage billions of records and lots of transactions every second.
6. … allows any remote computer or network workstation to access data in a database.
4. Fill in the gaps in the text.
The data in a database can be _1_ over the Web. A simple process called _2_ Web publishing converts a database report into an HTML document, which can be displayed by a browser. More sophisticated _3_ Web publishing produces data from a database on demand. HTML forms and XForms not only provide search capabilities, but can also be used to add or modify data in a _4_ with a Web browser. _5_ documents provide a Web-based data management tool that uses special _6_ as field names within a document.
Speaking. Discuss the following questions.
1. Are simple data management tools available?
2. Can you create your own data management software?
3. What kinds of tools are specially designed for creating and manipulating databases?
4. Is it possible to access a database over the Web?
Text C
Pre-reading task. Match the meaning of the following English words with the Russian equivalents.
1. conversion routine а) избыточность данных
2. data redundancy b) порядок сортировки
3. BLOB c) индекс базы данных
4. variable-length field d)конверсионная подпрограмма
5. primary key e) первичный ключ
6. sort order f) целочисленный тип данных
7. validation rule g) большой двоичный объект
8. fixed-length field h) поле неподвижной длины
9. integer data type i) правило ратификации
10. database index j) поле переменной длины
Reading. Read the text and try to guess the meaning of the words in bold. Check your variants in the dictionary.
DATABASE DESIGN
The key to an effective database is its initial design. In a well-designed database, data can be flexibly manipulated to produce timely, meaningful, and accurate information for decision making. Bad database design can lead to messy databases, lost records, and inaccurate data. The goal of good database design is to store data/information so that it is easy to access and maintain, but concise enough to take up as little disk space as possible.
The term database structurerefers to the arrangement of fields, tables, and relationships in a database. The first step in structuring a relational database is to determine what data must be collected and stored. To do so, a database designer might begin by consulting users and studying the current filing system to compile a list of available data as well as any additional data necessary to produce on-screen output or printed reports.
After the designer determines what data to store, the next step is to organize that data into fields. It is usually easy to break data into fields just by using common sense and considering how people might want to access the data. Any data that people would want to search for, sort on, or use in a calculation should be in its own field. The treatment of first and last names illustrates the concept of breaking data into fields. A database designer could definea field called Name to hold an entire customer’s name. With the entire name in one field, however, the database would not be able to access individual parts of the name, making it difficult to alphabetize customers by last name or to produce a report in which names appear in one field. That’s why the last names are stored in a different field than first names.
Although two people might have, for example, the same name or two paychecks might contain the same amount, a computer must have some way to differentiate between records. A primary keyis a field that contains data unique to a record.
The data that can be entered into a field depends on the field’s data type. From a technical perspective, data type specifies the way data is represented on the disk and in RAM. From a user perspective, the data type determines the way data can be manipulated. When designing a database, each field is assigned a data type. Data can be broadly classified as numeric or character. Character data contains letters, numerals and symbols not used for calculations. Numeric data contains numbers that can be manipulated mathematically by adding, averaging, multiplying and so forth. There are several numeric data types, including real, integer, and date. The real data type is used for fields that contain numbers with decimal places – prices, percentages, and so on. The integer data type is used for fields that contain whole numbers-quantities, repetitions, rankings, and so on. The date data type is used to store dates in a format that allows them to be manipulated, such as when you want to calculate the number of days between two dates.
The text data type is typically assigned to fixed-length fields that hold character data – people’s names, albums titles, and so on. Text fields sometimes hold data that looks like numbers, but doesn’t need to be mathematically manipulated. Telephone numbers and ZIP codes are examples of data that looks numeric, but is stored in text fields. A memo data type usually provides a variable-length field into which users can enter comments. The logical data type (sometimes called a Boolean or yes/no data type) is used for true/false or yes/no data using minimal storage space. Some file and database management systems also include additional data types, such as BLOBs and hyperlinks. A BLOB(binary large object) is a collection of binary data stored in a single field of a database. BLOBs can be just about any kind of data you would store as a file, such as an MP3 music track. The hyperlink data type stores URLs used to link directly from a database to a Web page.
The information produced by reports and processing routines is only as accurate as the information in the database. Unfortunately, data entry errors can compromise the accuracy and validity of a database. When designing a database, it is important to think ahead and envision potential data entry errors. Preventing every typographical error is not possible. However, it is possible to catch some of these errors by using field validation rules, list boxes, or lookups. A process called normalizationhelps create a database structure that can save storage space and increase processing efficiency. The goal of normalization is to minimize data redundancy – the amount of data that is repeated or duplicated in a database.
Records in a database can be organized in different ways depending how people want to use them. No single way of organizing the data accommodates everyone’s needs, but tables can be sorted or indexed in multiple ways. A table’s sort order is the order in which records are stored on disk. Sorted tables typically produce faster queries and updates. In a sorted table, new records are inserted to maintain the order. Most DBMSs use a sort key to determine the order in which records are stored. A table’s sort key is one or more fields used to specify where new records are inserted in a table. A database index can be used to organize data in alphabetic or numeric order. A database indexcontains a list of keys, and each key provides a pointer to the record that contains the rest of the fields related to that key.
Designing the database user interface can be a challenging task. If a company’s database includes multiple tables used by many different people, a professional user interface designer usually creates and maintains the user interface. Large databases might even require a group of user interface designers, meanwhile the interface for smaller databases, such as those used by small businesses or individuals, is most likely created by a single one.
A well-defined user interface for a database should be clear, intuitive, and efficient. A designer might consider the following principles:
1. Arrange fields in a logical order beginning at the top-left of the screen. The first fields should be those used most often or those that come first in the data entry sequence.
2. Provide visualclues to the entry areas. An edit box, line, or shaded area can delineate data entry areas.
3. Entry areas should appear in a consistent position relative to their labels. By convention, labels are placed left of the entry areas or above them.
4. Provide a quick way to move through the fields in order. By convention, the tab key performs this function.
5. If all fields do not fit on a single screen, use scrolling or create a second screen.
6. Provide buttons or other easy-to-use controls for moving from one record to another.
7. Supply on-screen instructions to help ensure that data is entered correctly. Web database can benefit from links to help pages.
After the design for the database structure is complete, it is time to load the database with an initial set of data. Data can be loaded into a database manually by using genericdata entry toolssupplied with the DBMS or by using a customized data entry module created by the database designer. Entering data manually can take a long time, however, and mistakes such as misspellings are common. If the data exists electronically in another type of database or in flat files, it is usually possible to transfer the data using a custom-written conversion routine or import and export routines. A conversion routine converts the data from its current format into a format that can be automatically incorporated into the new database. It takes some time and requires knowledge about database formats to write conversion routines, but for large databases, it’s much quicker to convert data than to re-enter it manually. Converting data also results in fewer errors.
Some DBMSs provide built-in import and export routines that automatically convert data from one file format to another. An import routine brings data into a database. For example, if data was previously stored as a spreadsheet file, an import routine in Microsoft Access can be used to transfer data from the spreadsheet to an Access database. In contrast, an export routine copies data out of a software package, such as spreadsheet software, and into the database. Typically, you would use either an import routine or an export routine to move data from one location to another, but not both.
Comprehension check. Choose the ending for each sentence from the two versions given.
1. The key to an effective database is
a) its initial design.
b) to determine what data must be collected and stored.
2. The term database structurerefers to
a) the arrangement of fields, tables, and relationships in a database.
b) the concept of breaking data into fields.
3. From a technical perspective, data typespecifies
a) the way data can be manipulated.
b) the way data is represented on the disk and in RAM.
4. Character data contains
a) letters, numerals and symbols not used for calculations.
b) numbers that can be manipulated mathematically.
5. The goal of normalization
a) is to produce timely, meaningful, and accurate information for decision making.
b) is to minimize data redundancy – the amount of data that is repeated or duplicated in a database.
6. After the design for the database structure is completed, it is time
a) to determine the order in which records are stored.
b) to load the database with an initialset of data.
Vocabulary practice
1. Which word does not belong to the group?
a) initial, original, primary, subsequent;
b) allow, permit, let, advice (verb + object + to);
c) current, visual, intuitive, efficiently;
d) carry out, execute, fulfill, specify;
e) reduce, decrease, minimize, grow up;
f) tool, device, equipment, gadget.
2. Fill in the blanks choosing from the variants given.
1. In a well-designed database, data can be … manipulated to produce timely, meaningful, and accurate information for decision making.
a) flexibly b) smoothly c) slowly d) hardly
2. The term database structurerefers to the … of fields, tables, and relationships in a database.
a) agreement b) allocation c) arrangement d) appointment
3. A primary keyis a … that contains data unique to record.
a) space b) field c) table d) file
4. When designing a database, you should … and envision potential data entry errors.
a) think ahead b) think about c) think over d) think out
5. Entering data … can take a long time, however, and mistakes such as misspelling are common.
a) electronically b) automatically c) in written form d) manually
6. A conversion routine … the data from its current format into a format that can be automatically incorporate into the new database.
a) provides b) transfers c) converts d) supplies
3. Transform the given sentences using the word in brackets without any change in meaning. You may omit, change or add words as required.
1. The goal of database design is to store information so that it is easy to access and maintain (aim).
2. The treatment of first and last name illustrates the concept of breaking data into fields (shows).
3. BLOBs can be just about any kind of data you would typically store as a file, such as an MP3 music track (usually).
4. The information produced by reports and processing routines is only as accurate as the information in the database (exact).
5. No single way of organizing the data accommodates everyone need’s, but tables can be sorted or indexed in multiple ways (satisfies).
6. Typically, you would use either an import routine or an export routine to move data from one location to another, but not both. (place).
4. Fill in the gaps in the text.
The first step in designing relational data base is to define its fields by specifying a _1_and data type. Integer, date and _2_ data types are used for fields that might be mathematically manipulated. The _3_data type is used for fixed-length fields containing text that is not intended to be mathematically manipulated. The _4_ data type is a variable-length field for entering text. The _5_ data type is used to store true/false or yes/no data. The _6_data type is used to store binary data, such as MP3 files or graphics. When designing fields, a database designer can also include field formats, field _7_rules, and lookup routines to reduce data entry errors.
Speaking. Discuss the following questions.
1. What is the goal of a well-designed database?
2. What does the term database structure refer to?
3. Speak on the first step in structuring a relational database? What is the next
step?
4. Why are last names stored in a different field than first names?
5. What does make each record unique?
6. How does a database designer know what data types to use?
7. Can a database designer prevent people from entering inaccurate data?
8. What is normalization?
9. What are the principles that a designer might consider to improve this database?
10. How is data loaded into database tables?
Text D
Pre-reading task. Match the meaning of the following English words with their Russian definitions.
1. SQL query a) запись
2. Database client software b) полное обновление
3. Relation database c) язык запросов
4. Record d) реляционная база данных
5. Global update e) ключевое слово
6. Parameter f) программное обеспечение клиента
базы данных
7. Keyword g) SQL-запрос
8. Query language h) слово-команда
9. Command word i) объединение таблиц
10. Joining tables j) параметр
Reading. Read the text and try to guess the meaning of the words in bold. Check your variants in the dictionary.
SQL
Addingrecords, finding information and making updates are all important aspects of database use. Most people who access a database on a “casual” basis interact with very simple user interfaces. These user interfaces shield users from the intricacies of sophisticated query languages. Nevertheless, a little background in query languages can help you understand the power and capabilities of databases.
Query languages like SQL (Structured Query Language) typically work behind the scenes as an intermediary between the database client software provided to users and the database itself. Database client software provides an easy-to-use interface for entering search specifications, new records, data updates, and so on. The client software collects your input, and then converts it into an SQL query, which can operate directly on the database to carry out your instructions.
An SQL query is a sequence of words, much like a sentence. Most implementations of SQL accept either uppercase or lowercase keywords.
The SQL query language provides a collection of special command words called SQL keywords, such as SELECT, FROM, INSERT, and WHERE, which issue instructions to the database. Most SQL queries can be divided into three simple elements that specify an action, the name of database table, and a set of parameters. Let’s look at each of these elements.
An SQL query typically begins with an action keyword, or command, which specifies the operation you want to carry out. For examples, the command word DELETE removes a record from a table, the command word CREATE creates a database or table, the command word INSERT is used to add a record, the command word JOIN uses the data from two tables, SELECTsearches for records and UPDATE changes data in the field.
SQL keywords such as USE, FROM, or INTO can be used to construct a clause specifying the table you want to access. The clause consists of a keywords followed by the name of the table. For example, the clause FROM Tracks indicates that you want to use the Tracks table from the Vintage Music Shop’s database.
The term parameter refers to detailed specifications for a command. Keywords such as WHERE usually begin an SQL clause containing the parameters for a command.
One of the most common database operations is to query for a particular record or group of records by using the SELECT command. The phrase, for example, SELECTAlbumTitle, Album Cover specifies that the database should show you only the album title and cover, and until you confirm that this is the album you are interested in, it will not show you additional information such as the price or list of tracks.
You can change records in a database only if you have authorization to do so. At Vintage Music Shop’s site, for example, customers do not have authorization to change album prices or alter the name of the songs on an album. The process of purchasing an album, however, does cause an update in the whole database. Your purchase just reduces the number of albums in the shop’s inventory. To accomplish this update, one of the software modules in the shop’s inventory system issues an SQL UPDATE command to reduce the number in the InStock field record. In addition to changing the data in a single record, SQL can perform a global update that changes the date in more than one record at a time. It means that it is possible to update a group of records. Suppose you’re Vintage Music Shop’s marketing manager, and you want to put all The Rolling Stones albums on sale by reducing the DiscountPrice to $9.95. You could do it the hard way by searching for an ArtistName field that contains “Rolling Stones”, adjusting the DiscountPrice field for that record, and then looking for the next Rolling Stones album. However, it would be easier to change all records with a single command. The following SQL statement accomplishes this global update:
UPDATE Albums
SET DiscountPrice = 9.95
WHERE ArtistName = ”Rolling Stones”
Let’s see how this command performs a global update. The UPDATE command means you want to change the data in some or all of records. Albums is the name of the record type containing the data you want to change. SET DiscountPrice = 9.95 tells the DBMS to change the data in the DiscountPrice field to $9.95. WHERE ArtistName = ”Rolling Stones” tells the DBMS to change only those records where the artist name is Rolling Stones. Although the global update function is powerful, it works only for records that have similar characteristics.
Recall that the process of normalization creates tables that can be related by fields that exist in both tables. In SQL terminology, the creating a relationshipbetween tables is referred to as joining tables. To take advantage of the relationship between two tables, you first have to join the tables. Why? Remember that in relational database, the tables are essentially independent unless you join them together. The SQL JOIN command allows you to temporarily joinand simultaneously access the data in more than one table.
SQL is a very extensive and powerful language that can be used not only to manipulate data, but also to create databases, tables and reports. Because SQL is one of the most popular database tools, many computer professionals consider SQL fluency as essential career skill.
Comprehension check. Match the beginning of the sentences in the first column with the endings in the second.
| 1.Adding records, finding information, and making updates 2. Query languages like SQL typically work behind the scenes 3. Database client software provides 4. An SQL query is 5. The process of purchasing an album 6. The SQL JOIN command allows you 7. You can change data in a database | a) as an intermediary between database client software provided to users and the database itself. b) are all important aspects of database use. c) a sequence of words, much like a sentence. d) only if you have authorization to do so. e) an easy-to-use interface for entering search specifications, new records, data updates and so on. f) does cause an update in the whole database. Your purchase just reduces the numbers of albums in the shop’s inventory. g)to temporarily access data in more than one table |
Vocabulary practice
1. Put the letters in the words in brackets into the correct order.
1. A little … in query languages can help you understand the power and capabilities of databases (roducknabg).
2. An SQL query typically begins with an action …, or command, which specifies the operation you want to carry out (weykdor).
3. The clause consists of a keywords followed by the name of the … (ablet).
4. Your … just reduces the numbers of albums in the shop’s inventory (sacherup).
5. The term … refers to detailed specifications for a command (earpmaret).
6. Although the global update function is powerful, it works only for … that have similar characteristics (coerdrs).
2. Fill in the blanks choosing from the variants given.
1. Most people who access a database on a “casual” basis … with very simple user interface.
a) manipulate b) work c) operate d) interact
2. A little … in query languages can help you understand the capabilities of databases.
a) certainty b) background c) career skills d) experience
3. The SQL query language provides a collection of special command … called SQL keywords, such as SELECT, FROM, INSERT, and WHERE, which issue instructions of the database.
a) words b) passwords c) names d) numbers
4. Most SQL queries can be divided into three simple elements that … an action, the name of database table, and a set of parameters.
a) execute b) indicate c) construct d) specify
5. Customers do not have … to change album prices or alter the name of the songs on an album.
a) authorization b) rights c) permission d) possibilities
6. SQL is a very extensive and powerful language that can be used not only to … data, but also to create databases, tables and reports.
a) enter b) manipulate c) to make updates d) input
3. Match the beginnings and the endings of the steps given and put them into correct order.(According to the text.)
| 1. SET DiscountPrice = $9.95 tells 2. WHERE ArtistName = ”Rolling Stones” tells 3. Albums is 4. The UPDATE command means 5. It means that 6. SQL can perform a global update | a) the name of the record type containing the data you want to change. b) to change the data in the DiscountPrice field to $9.95. c) to change only those records where the artist name is Rolling Stones. d) you want to change the data in some or all of records. e) that changes the data in more than one record at time. f) is possible to update a group of records. |
4. Fill in the gaps in the text.
SQL is a database query language that typically works behind the scenes as an intermediary between the database _1_ software provided to users and the database itself. Although the specifications for searchers and other database tasks are collected by easy-to use graphical user interfaces, those specifications are converted into SQL _2_ which can communicate directly with the database. An SQL query contains SQL _3_ such as SELECT, FROM, INSERT, JOIN and WHERE, plus _4_ that specify the details of the command. Records can be removed from a database using the SQL _5_command. Record can be added to a table using the SQL _6_ command. To search for data, you can use the SQL _7_ command. To change or replace the data in a field requires the SQL _8_ command.
Speaking. Discuss the following questions.
1. What are the most important aspects of database use?
2. Why is so important to have a little background in query languages?
3. What does the abbreviation SQL stand for?
4. How does a query language like SQL work?
5. What does a simple SQL query look like?
6. How does SQL specify the action that someone wants carried out in the data base? Speak on the most commonly used SQL command words.
7. How does SQL specify which table to use?
8. How do SQL queries carry out searches?
9. Is it possible to change the contents of records or to update a group of records? What does the process of purchasing cause?
10. How is the data retrieved from more than one table at a time? What command does allow you to access the data in more than one table?
Critical thinking. Read the article and express your opinion on the problem.
Privacy
You might be astonished by the amount of information stored about you in computer databases. Your bank has information on your financial status, credit history, and the people, organizations, and businesses to which you write checks. School records indicate something about your ability to learn and the subjects that interest you. Medical records indicate the state of your health. Credit card companies track the places you shop and what you purchase in person, by mail, or on the Web. Your phone company stores your phone number, your address, and a list of the phone numbers you dial. The driver’s license bureau has your physical description. Your internet cookies track many of the Web sites you frequent. By compiling this data – a process sometimes referred to as “profiling” – an interested person or company could guess some very private things about you, such as your political views or even your sexual orientation.
When records were stored on index cards and in file folders, locating and distributing data constituted a laborious process that required hand transcriptions or photocopies of piles of papers. Today, this data exists in electronic format and easy to access, copy, sell, shop, consolidate, and alter.
Privacy advocates point out the potential for misusing data that has been collected and stored in computer database. In response to terrorist threats, the Pentagon is working on several controversial projects designed to mine data from databases that store information about passports, visas, work permits, car rentals, air-line reservations, arrests, bank accounts, school grades, medical history, and fingerprints. Government data miners believe that data mining could uncover terrorists. Privacy advocates note, however, that every data set contains patterns. The big question is whether any set of seemingly innocent activities, such as credit card purchases, can be correlated with impending terrorist acts. The potential for error and privacy violation in generalized data mining projects is sobering. Privacy advocates are encouraging lawmakers to closely monitor government snooping and restrict private-sector sale and distribution of information about individuals. Some legislation is in place for certain private-sector institutions. For example, the 1999 Financial Services Modernization Act requires financial institutions to supply clients with an annual notice explaining how personal information is collected and shared. This legislation also required financial institution to provide a way for clients to opt out of such information exchanges.
The issue of privacy is not simple. Information about you is not necessarily “yours”. Although you might “reveal” information about yourself on an application form, other information about you is collected without your direct input. For example, suppose you default on you credit card payment. The credit card company has accumulated information about your delinquent status. Shouldn’t it have freedom to distribute this information, foe example, to another credit company?
People aren’t always unwilling victims of privacy violations. Many individuals knowingly let companies gather profiling information to get free products. For example, thousands of people signed up for Google’s Gmail service even though they knew their e-mail massages could be scanned to develop marketing profile.
Unfortunately, private information can be garnered from your computer without your permission. Spyware is a type of software containing code that tracks personal information from your computer and passes it on to third parties, without your authorization or knowledge. Spyware might be embedded in an application that you download, or it can download itself from unscrupulous Web-sites – a process called a “driveby download”. Databases containing personal information do offer positive benefits. For example, many web surfers appreciate the shortcuts offered by software agents that assemble a customer profile in order to recommend books, CDs, videos, new articles, and other targeted goods and services. These users might willingly give up some measure of privacy for the convenience afforded by these agents.
The electronic privacy issue appears to be heading toward some type of compromise between strict privacy and wholesale collection/distribution of personal data.
What do you think?
1. Do you think data about you should be distributed only after your permission is obtained?
2. Can you identify an actual incident when you discovered that data about you was distributed without your approval?
3. Do you think the information you provide on paper forms is more private than the information you enter into Web-based format?
4. Have you thought about ways to protect your privacy?
Projects. Choose and perform one of the projects given.
1. A friend wants to create a table to store information about a collection of old books. List the fields you might include in the table to store information about the book. For each field, specify the field name, data type (text, numeric, date, etc) and field length. Indicate primary key(s) and describe in writing how you would sort and/or index the data.
2. Computer databases often store personal information about the citizens of more than one country, yet privacy expectations and laws differ. For this project, explore the differences in privacy laws around the globe. Which countries have the strongest privacy laws and which have the weakest? Which laws would govern the data stored by multinational companies? As a global consumer, which databases would concern you most for potential privacy violations? Consolidate your thoughts into a one- to two-page paper and submit to your instructor
Final test. Do the tasks in the following test.
1. A(n) … file is a structured file containing only one record type.
2. All of the following are considered advantages of using static Web publishing to display data on a Web page, EXCEPT … .
a) you data remains secure
b) most entry-level DBMSs provide the capability to produce an HTML page
c) users can change your data d) it provides a “snapshot” of your data
3. Modern database software supports data …, which means keeping data separated from the program modules that manipulate the data.
4. The first step to organize relational database is to organize data into field. (True/ False)
5. In a relational database, an attribute is equivalent to a record. (True/False)
6. A(n) … is a collection of data fields that pertain to an entity, such as a person, place, or thing.
7. One of the goal of normalization process is to minimize data … .
8. SQL … include SELECT, FROM and INSERT.
9. ASP, CGI, and PHP are used to create XML documents that are processed on a server before being sent to your browser. (True/False)
10. In SQL, the JOIN command allows you to add fields to a database. (True/False)
11. Spreadsheet software typically includes some data management features suitable for working with relational database. (True/False)
12. A database index has no bearing on the physical sequence of records stored on disk. (True/False)
13. Data … refers to the use of statistical tools for automated extraction of predictive information from database.
14. An SQL query is a sequence of words, much like a sentence. (True/False)
15. Once a table’s sort key has been added, it cannot be changed. (True/False)
16. In an ERD, relationships and … are shown by connecting lines.
17. A primary … contains data unique to a record.
18. The term “parameter” refers to detailed specifications for a command. (True/False)
19. Real, integer, text, logical, BLOB and date are examples of data … .
20. A database consists of one or more record … that contain data.
.