Computer World. Матросова Т.А. - 56 стр.

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УлГТУ | Ульяновск

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55
4. What is DBMS expected to do?
5. When did the first commercial DBMS appear?
6. What is the advantage of DBMS over a file system?
7. What does DBMS support to avoid undesirable consequences of
simultaneous access?
Exercise 2. Read the paragraph. Some of the words are missing: they are listed at the
end of the paragraph. Put the right word in each space.
Relational Database Systems
Following a famous paper written by Ted Codd in 1970, (1)… systems
changed significantly. Codd proposed that database systems should present the
user with a view of data organized as (2)… called relations. Behind the scenes,
there might be a complex data (3)… that allowed (4)… response to a variety of
(5)… . But, unlike the user of earlier database systems, the (6)… of a relational
system would not be concerned with the storage structure. Queries could be
expressed in a very (7)… language, which greatly increased the (8)… of database
programmers.
tables, database, user, rapid, high-level, structure, queries, efficiency
Exercise 3. Find the paragraph dealing with the drawbacks of file systems. Translate
it in w ritten form.
Exercise 4. Write an abstract of the text.
TEXT 2
Look through the text and define it’s theme. Decide on a suitable title for the
text. Make up a plan of the text and retell the text briefly according to the plan.
The first important applications of DBMS's were ones where data was composed
of many small items and many queries or modifications were made. Here are some of
these applications.
Airline Reservations Systems
In this type of system, the items of data include:
1. Reservations by a single customer on a single flight, including such infor-
mation as assigned seat or meal preference.
2. Information about flights – the airports they fly from and to, their departure
and arrival times, or the aircraft flown, for example.
3. Information about ticket prices, requirements, and availability.
Typical queries ask for flights leaving around a certain time from one given
city to another, what seats are available, and at what prices. Typical data
modifications include the booking of a flight for a customer, assigning a seat, or
indicating a meal preference. Many agents will be accessing parts of the data at any

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