IT APPLICATION TOOLS IN BUSINESS
TYPE OF EXAM
The Hierarchy of Data
I.
II.
III.
IV.
V.
Hierarchy
Multiple choice (Database)
Identification (SQL Commands, Statement)
PARTS (impress)
SQL, create a statement codes, select statements
SQL
a. What is the result sa statement
b. Update, increase, insert, select
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Field
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LESSON 1: DATABASE MANAGEMENT
Database
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Collection of data organized so you can access,
retrieve, and use it
Database
software
also
called
database
management system (DBMS)
Database software allows you to
o Create database
o Add, change, and delete data
o Sort and retrieve data
o Create forms and reports
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How are data and information related?
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Data is raw facts
Information is data that is organized and meaningful
receipt
Computers process data into information
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Data integrity
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Combination of one or more characters
Smallest unit of data user accesses
o Field size defines the maximum number
of characters a field can contain
o Field name uniquely identifies each field
o Data type specifies kind of data field
contains
common data types
Data and Information
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Database contains files, file contains records, record
contains fields, field contains characters
Degree to which data is correct
o Garbage in, garbage out (GIGO)—
computer phrase that means you cannot
create correct information from
incorrect data
o Garbage in, Garbage out, Data integrity
is lost
Text (also called alphanumeric)—letters, numbers,
or special characters
Numeric numbers only
AutoNumber unique number automatically assigned
to each new record
Currency dollar and cent amounts or numbers
containing decimal values
Date month, day, year, and sometimes time
Memo lengthy text entries
Yes/No (also called Boolean)— only the values Yes or
No (or True or False)
Hyperlink Web address that links to document or
Web page
Object (also called BLOB for binary large object)—
photograph, audio, video, or document created in
other application such as word processing or
spreadsheet
Record
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Group of related fields
Key field, or primary key, uniquely identifies each
record
What are the qualities of valuable information?
Data file
1.
2.
3.
4.
5.
6.
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Accurate
Verifiable
Timely
Organized
Accessible
Useful
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Collection of related records stored on disk
IT APPLICATION TOOLS IN BUSINESS
Maintaining Data
database approach
File Maintenance
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Procedures that keep data current
o Adding records
o Changing records
o Deleting records
Strengths of the database approach
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Why do you add records?
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Add new record when you obtain new data
Why do you change records?
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Many programs and users can share data in database
Secures data so only authorized users can access
certain data
Reduced data redundancy
Improved data integrity
Shared data
Easier access
Reduced development time
Database Management Systems
Correct inaccurate data
Update old data
popular database management systems (DBMSs)
Why do you delete records?
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When record no longer is needed
Some programs remove record immediately, others
flag record
Validation
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Process of comparing data with a set of rules to find
out if data is correct
Reduce data entry errors and enhance data integrity
before program writes data on disk
Types of validity checks
1. Check Digit number(s) or character(s) appended
to or inserted into a primary key value to confirm
accuracy of primary key value
2. Alphabetic/ Numeric Check ensures correct type
of data entered
3. Range Check determines whether number is
within specified range
4. Completeness Check verifies that a required field
contains data
5. Consistency Check tests for logical relationship
between two or more fields
Data dictionary
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Query
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File Processing Versus Databases
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Request for specific data from a database
Query language consists of simple, English-like
statements that allow users to specify data to
display, print, or store
Form
File processing system
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Contains data about each file in database and each
field within those files
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Each department or area within organization has
own set of files
Records in one file may not relate to records in any
other file
May have weaknesses:
o Data redundancy— same fields stored in
multiple files
o Isolated data—data stored in separate
files so it is difficult to access
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Window on screen that provides areas for entering
or changing data in database
Used to retrieve and maintain data in a database
Form that sends data across network or Internet is
called e-form, short for electronic form
Report generator
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Allows user to design a report on screen, retrieve
data into report design, then display or print reports
IT APPLICATION TOOLS IN BUSINESS
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Also called report writer
data security
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DBMS provides means to ensure only authorized
users can access data
Access privileges define activities that specific user or
group of users can perform
o Read-only privileges - user can view
data, but cannot change it
o Full-update privileges - user can view
and change data
Backup and Log
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Backup is a copy of the entire database
Log is a listing of activities that change database
contents
o DBMS places three items in log: before
image, actual change, and after image
Recovery utility
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Relational database
Uses logs and/or backups to restore database when
it is damaged or destroyed
Rollforward—DBMS uses log to re-enter changes
made to database since last save or backup. Also
called forward recovery
Rollback—DBMS uses log to undo any changes made
to database during a certain period of time ▪Also
called backward recovery.
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Stores data in tables that consist of rows and
columns
o Each row has primary key
o Each column has unique name
Stores data relationships
Uses specialized terminology
Relational, Object-Oriented, and Multidimensional
Databases
Data model
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Rules and standards that define how database
organizes data
Defines how users view organization of data
Three popular data models
o Relational
o Object-oriented
o Object-relational
o Multidimensional
Structured Query Language (SQL)
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Allows you to manage, update, and retrieve data
Has special keywords and rules included in SQL
statements
What are guidelines for developing a database
1. Determine the purpose of the database
2. Design the tables
a. Design tables on paper first
b. Each table should contain data about
one subject
3. Design the records and fields for each table
a. Be sure every record has a unique
primary key
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IT APPLICATION TOOLS IN BUSINESS
b. Use separate fields for logically distinct
items
c. Do not create fields for information that
can be derived from entries in other
fields
d. Allow enough space for each field
e. Set default values for frequently entered
data
4. Determine the relationships among the tables
calculus. It includes also command to insert,
delete and modifying in the database.
3. View Definition – the SQL DDL also includes
commands for defining views.
4. Authorization – the SQL DDL includes commands
for specifying access rights to relation and views.
5. Integrity – the SQL provides forms of integrity
checking. Future products and standard of SQL
are likely to include enhanced features for
integrity checking.
role of the database analyst and administrator
Relational Data Structure
Database analyst (DA)
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Focuses on meaning and usage of data
Decides proper placement of fields, defines
relationships, and identifies users’ access privileges
Database administrator (DBA)
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Creates and maintains data dictionary, manages
database security, monitors database performance,
and checks backup and recovery procedures
A relational data structure is a collection of tables or
relations.
o A relation is a collection of rows or tuples
o A tuple is a collection of columns or
attributes
o A domain is a pool of values from which
the actual attribute values are taken.
CREATE TABLE CODE
create table stud_info
SQL
(stud_no numeric(6) not null,
SQL
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last_name varchar(20) not null,
The structure query language is language that
enables to create and operate on relational
database, which are sets of related information
stored in tables. It has clearly established itself as the
standard relational database language. It is basically
used to pass the query to retrieve and manipulate
the information from database, depending upon the
nature of query.
SQL can:
o Create Schemas in the DBMS
o Alter Schemas
o Add data
o Remove data
o Change data
o Access Data
first_name varchar(20) not null,
middle_name varchar(20),
course varchar(30) not null,
primary key (stud_no)
);
describe stud_info;
ALTER statements: To modify an existing database
object.
alter table stud_info
Processing Capability of SQL:
add (address varchar(60) not null);
1. Data Definition Language (DDL) – it provides
commands for defining relations schemas,
deleting relations, creating index, and modifying
relations schemas.
2. Data Manipulation Language (DML) – it includes
the queries language based on both the
relational algebra and the tuples relational
Dropping a column from a table:
alter table stud_info
drop column address;
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IT APPLICATION TOOLS IN BUSINESS
DROP statements: To destroy an existing database,
table, index, or view. If a table is dropped all records
held within it are lost and cannot be recovered.
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drop table Stud_info;
ADDITIONAL COMMAND LISTS:
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alter table stud_info
modify course varchar(50);
alter table stud_info
add (birthday date not null);
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insert into stud_info
values(92213,'Maligsa','Katherine','Esguerra','BS
Computer Science','11/30/1995');
FROM CAR
WHERE COLOR != 'RED';
SELECT REGNO, COLOR, PRICE
update stud_info
FROM CAR
set middle_name = 'Unica'
WHERE COLOR != 'RED';
DATE
where first_name = 'Rickz'
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DELETE statement removes one or more records from a
table. A subset may be defined for deletion using a
condition, otherwise all records are removed.
Date comparisons can be tricky
You can use all the normal comparators with dates.
SELECT name, dob
from driver
delete from stud_info
where DOB = ‘1986-12-03’;
where first_name = 'Eric'
SELECT name, dob
SELECT statement returns a result set of records from
one or more tables.
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Valid comparisons include =, !=, <>, <=, >, >=
SELECT *
UPDATE statement that changes the data of one or
more records in a table. Either all the rows can be
updated, or a subset may be chosen using a condition
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Formatting
o SPACES do not matter
o NEWLINES do not matter
o Good practice to put ; at the end of the
query.
o CASE (except between single quotes)
does not matter.
Comparisons
INSERT statement adds one or more records to any
single table in a relational database.
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o SELECT<attribute list>
o FROM<table list>
o WHERE<condition>
EXAMPLE:
o SELECT *
o FROM CAR
o WHERE COLOR = 'RED';
from driver
WHERE DOB >= ‘1981-01-01’;
WHERE specifies which rows to retrieve
GROUP BY groups rows sharing a property so that
an aggregate function can be applied to each group
having group.
HAVING selects among the groups defined by the
GROUP BY clause.
BETWEEN
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ORDER BY specifies an order in which to return
the rows.
o Syntax:
When dealing with dates sometimes you want to test
to see if a field value falls between two dates.
The easiest way to do this is with BETWEEN
NULL
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NULL indicates that something has no value
IT APPLICATION TOOLS IN BUSINESS
SELECT regno
from car
WHERE OWNER = ' ';
LIKE
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Sometimes you want to have a rule involving partial
strings, substrings, or wildcards
LIKE does this, and is a slot-in replacement for ‘=‘
If the string contains ‘%’ or ‘_’, LIKE uses them to
support wildcards.
o % - Matches 0 or more characters in the
string
o _ - Matches exactly 1 character in the
string
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