Module 2: Database Management (with solved solutions)
Data correct answers
Computers store data in file, which can be defined as correct answers simplify as a collection of
data.
A computer file is organized in a correct answers particular way with well-defined structure for
the information in the file.
A computer file consists of a collection of correct answers records each of which is made up of
fields.
The various fields consist of correct answers groups of characters
Byte correct answers the smallest unit of storage in byte, which consists of 8 bits,this byte can
represent numbers, characters,or parts or images.
Character correct answers the unit of interest is processing business data is the character for
example,the number 9 or letter A. A character represents one byte of storage so one 8-bit = one
letter or number.
We generally do not work directly with characters but rather with groups of characters that have
some meaning,such as Smith or 599
A= One Character
Fields correct answers are groupings of characters are called fields,and we identify them with a
name. Smith is an employee's surname and 599 is the Smith's department number.
Data correct answers groups of fields are combined to form a logical record.
Database Keys correct answers are key elements of relational database
Each row in a table will have a correct answers unique key
A key is a designated field of correct answers a table that is used by database systems to tell the
rows of a table apart from each other, and how rows in one table relate to correspondencing rows
in another table.
Primary Key correct answers a unique key or primary key is a key that uniquely defines the
characteristics of each row.
The primary key has a correct answers consists of characteristics that cannot collectively be
duplicated by any other row.
, In a telephone book the primary key is the surname of the person.
A secondary key correct answers in the case of the telephone book, then is the person's first
name or initial.
The telephone book,then is arranged in sequence on the primary key (last name),and within the
primary key is arranged in order by the secondary key (first name)
Foreign Key correct answers is a key in one table that is the primary key in another table,it is
used to create a link a relationship between two tables in relational database.
Fields designated as keys correct answers are also used as a basis for retrieving information
from a file.
For example : An inventory part number may be the key for retrieving information from and
inventory file about the quantity of the part on hand.
Access correct answers
There are two major types of files correct answers Sequential and direct access
Sequential Files were correct answers the first type of secondary storage
All records are kept in some correct answers sequence such as numeriacl order by Social
Security numbers. Most of us will encounter sequential access files only in special
circumstances.
Records in this type of file correct answers are located one after another according to given
sequence. For example : the record with payroll number 1 is followed by the record with number
2,etc
With sequential file you cannot correct answers find specific record,such as the person with
payroll number 127,unless you read the entire file until you locate a record with payroll number
127
Direct Access Files correct answers uses a physical medium programming,which facilitate the
storage an retrieval of specific records.
These files are correct answers at the heart of database management systems and most of today's
file storage technology, the reservations data in an airline's reservations system are stored on
direct-acccess files.
Storage Media correct answers 1.Platter: one type of disk consists of series of platters mounted
on a spindle, the top and bottom of each platter (except for the very top and bottoms ones) are
coated with a magnetic material like that on a music cassette tape.
Data correct answers
Computers store data in file, which can be defined as correct answers simplify as a collection of
data.
A computer file is organized in a correct answers particular way with well-defined structure for
the information in the file.
A computer file consists of a collection of correct answers records each of which is made up of
fields.
The various fields consist of correct answers groups of characters
Byte correct answers the smallest unit of storage in byte, which consists of 8 bits,this byte can
represent numbers, characters,or parts or images.
Character correct answers the unit of interest is processing business data is the character for
example,the number 9 or letter A. A character represents one byte of storage so one 8-bit = one
letter or number.
We generally do not work directly with characters but rather with groups of characters that have
some meaning,such as Smith or 599
A= One Character
Fields correct answers are groupings of characters are called fields,and we identify them with a
name. Smith is an employee's surname and 599 is the Smith's department number.
Data correct answers groups of fields are combined to form a logical record.
Database Keys correct answers are key elements of relational database
Each row in a table will have a correct answers unique key
A key is a designated field of correct answers a table that is used by database systems to tell the
rows of a table apart from each other, and how rows in one table relate to correspondencing rows
in another table.
Primary Key correct answers a unique key or primary key is a key that uniquely defines the
characteristics of each row.
The primary key has a correct answers consists of characteristics that cannot collectively be
duplicated by any other row.
, In a telephone book the primary key is the surname of the person.
A secondary key correct answers in the case of the telephone book, then is the person's first
name or initial.
The telephone book,then is arranged in sequence on the primary key (last name),and within the
primary key is arranged in order by the secondary key (first name)
Foreign Key correct answers is a key in one table that is the primary key in another table,it is
used to create a link a relationship between two tables in relational database.
Fields designated as keys correct answers are also used as a basis for retrieving information
from a file.
For example : An inventory part number may be the key for retrieving information from and
inventory file about the quantity of the part on hand.
Access correct answers
There are two major types of files correct answers Sequential and direct access
Sequential Files were correct answers the first type of secondary storage
All records are kept in some correct answers sequence such as numeriacl order by Social
Security numbers. Most of us will encounter sequential access files only in special
circumstances.
Records in this type of file correct answers are located one after another according to given
sequence. For example : the record with payroll number 1 is followed by the record with number
2,etc
With sequential file you cannot correct answers find specific record,such as the person with
payroll number 127,unless you read the entire file until you locate a record with payroll number
127
Direct Access Files correct answers uses a physical medium programming,which facilitate the
storage an retrieval of specific records.
These files are correct answers at the heart of database management systems and most of today's
file storage technology, the reservations data in an airline's reservations system are stored on
direct-acccess files.
Storage Media correct answers 1.Platter: one type of disk consists of series of platters mounted
on a spindle, the top and bottom of each platter (except for the very top and bottoms ones) are
coated with a magnetic material like that on a music cassette tape.
