DATABASE TERMS
1. With regard to databases, what is a table?
A table a collection of related information about a particular topic. A table might contain
the names and addresses of a company's customers or a table might contain a list of the
company's inventory. Another name for a table is file.
2. With regard to databases, what is a field?
As discussed above, a file is a collection of related information. Every file is divided into
columns called fields. A field contains one category of information relating to the subject
of a file. If the topic of the file is a company's customers, the file would contain fields
such last name or first name. Each field must have a unique field name.
3. List seven different field types a table might contain.
Numeric, text, date or time, logical, counter, memo and binary are the field types that can
be found in a database.
4. With regard to databases, what is a record?
If you read across the fields (columns) in a table and collect one piece of information
from each field, the information you gather is called a record. Each record occupies in
one row in the table.
5. What is a flat file program?
The term database is commonly used to describe any software program that allows you to
manipulate the fields and records stored in table. More properly speaking, there are two
categories of programs used to manipulate the information stored in a table, flat file
programs and database programs, also called database management systems (DBMS). A
flat file program is software that lets you manipulate the records in one file at a time.
6. Give two examples of programs in common use that, while not referred to as
database programs, are powered by a database.
Many programs used daily by people have placed an interface or 'frontend' on a database
and can be used to perform a number of 'database like' tasks. One type of program is
referred to as personal information managers (PIM); an example of a PIM is Outlook.
Another type is personal finance software. The most popular example of personal finance
software is Quicken.
When using these programs, there is no need to create tables or learn database command
and terminology. The interface hides the database but lets you take advantage of the
database commands and features discussed in the questions below.
7. What a database?
A record is a collection of field information. A table is a collection of records and a
database is a collection of related tables or files. For example, a department store might
have a table for its customers, one for its salespeople and one for inventory. A database
would contain all three tables and would allow a manager to draw information from all
three tables to create an invoice or print a report.
What is a DBMS?
The letters DBMS stand for database management system (or software). A DBMS is a
collection of tables and programs used to store information. A DBMS also allows you to
easily access, modify and retrieve that information. Using the programs included in the
DBMS, you can display or print all of the records in one or more tables or select just
some of the records that meet user defined conditions.
8. What is data redundancy? What can data redundancy lead to?
Data redundancy means that the same data is stored in several files. For example, if SSU
used flat file programs (it doesn't) your address might be stored in a table maintained by
Admissions and Records and another table maintained by Financial Aid.
Data redundancy can lead to a lack of data integrity, a situation where the data is correct
in one location but not others. For example, you move and inform Admissions and
Records of your address change but you forget to inform Financial Aid that your address
has changed. Admissions and Records will update your record in their table but your
address is not updated in your record kept by Financial Aid.
9. What is the chief difference between a flat file program and a database?
A flat file program can only work with one file at a time. The use of flat file programs in
a large organization such as Sonoma State would encourage data redundancy because
every department collects and maintains its own files.
By contrast, since a true database program can work with several related files at one time
and maintains all data in one central location, each department accesses the same data. If
Admissions and Records changes your address, the next time someone in Financial Aid
looks up your address, they will see the correct information.
10. List six data management functions you can perform with a flat file program or
a DBMS.
Data management and flat file programs lets you create, edit and delete records in a
database. You can also use data management and flat file programs to sort (rearrange)
records, filter or query a table to view only records that meet certain predefined
conditions and to generate reports, printed copies of some or all of the database's records.
11. Describe the difference between accessing database records sequentially and
directly.
There are two ways to access records in a database, sequentially or directly. With
sequential access, to access a record, you must first go past all the records stored in front
of the record you want. With direct access, you can go immediately to the desired record.
A musical analogy to sequential and direct access is finding a song on an audio tape vs.
finding a song on a CD. With an audio tape, if you want to play song #6, you must fast
forward past the first five songs; this is sequential access. With a CD, you can jump
directly to song six; this is direct access. Another term for sequential access is serial
access while another term for direct access is random access.
12. Give an example of when sequential access and an example of when direct access
might be used to access records stored in a database.
When you want to perform a number of operations at one time, sequential access is ideal.
For example, if you want to print paychecks for your employees or print out a list of all
the items in inventory, you could use sequential access and not miss the convenience of
direct access. Performing many operations at once is sometimes called batch processing.
When you want to look up a particular piece of information, you would use direct access.
For example, if a customer wanted to know the status of her order, you would want
access her record directly.
13. What role does an index play in accessing records?
An index is a separate file maintained by a database program and allows direct access to
the records found in the database. The index is based on a piece of unique information
found in each record, something that distinguishes a record from all others. A social
security number would work well in an index because no two people have the same
social security number. However, last names would not work because several people in a
large database might share the same last name. A database's index plays a role similar to
the index in a book. Just as you can look up a term in a book's index to quickly locate that
information on that term in the book, an index allows you to jump right to a particular
record in a database.
14. What does it mean to filter a database?
There are times when you want to view or print only some of the records in a database.
Perhaps you only want to see the records of people who live in a particular zip code. To
filter a database means to set up conditions records must meet for selection. Once you
apply the filter to the records, only records that meet the conditions will be displayed. For
example, you might want to do a mailing to customers who live in zip code 94952. You
would filter the database by setting conditions such that the zip code field of a record
must contain 94952. When the filter was complete, only the records with 94952 in the zip
field would be displayed.
15. What are comparison criteria?
Comparison criteria are the conditions records must meet in order to be selected by a
filter command. Comparison criteria are composed of three parts: the field(s) to be
evaluated, the condition(s) to be met and the relation that exists between the evaluated
field(s) and the condition(s). In the example above, zip code equal to 94952, zip is the
field to be evaluated, 94952 is the condition and 'equal to' is the relationship between the
field and the conditions.
16. List the six relational operators used with comparison criteria and the
keystrokes needed to include the operators in a filter.
When establishing the relationship between the data in the field to be evaluated and the
conditions, six relational operators are used. The table below lists the operators and the
symbols or keystrokes used to indicate the relational operators.