Test Review Exam 2: Prof. Reinhardt Computer Resource Center
REACH 2015 1 Slide 2 Test Overview Very Little Application Problems
Wiley Chapters 5, 7, 11 Queries: Append, Delete, Update, Calculate,
Select Types of Relationships (One-many, many- many, one-one) Other
Assess Database Concepts and Definitions 2 Slide 3 Database Design
Basic Terminology: A table consists of data that is arrayed in rows
and columns. A row of data is called a record. A column of data is
called a field. Thus, a record is a set of related fields. The
fields in a table should be related to one another in some way. 3
Slide 4 Basic Terminology Primary key field is a field in which
each record has a unique value. e.g. The SSN Foreign key is the
primary key of another table. e.g. suppose we need to link the
employee table with the Hours worked table for payroll purposes.
The Employee ID number (EIN) is the primary key of the employees
table but the foreign key of the hours worked table. * Every
foreign key must be associated with a primary key in another table.
4 Slide 5 Basic Terminology A form is a database object that is
created from an existing table to make the process of entering data
more user-friendly A query is the database equivalent of a question
that is posed about data in a table (or tables). Queries can be
designed to search multiple tables but these tables should be
connected by a join operation. 5 Slide 6 Cardinality of
Relationships In a one-to-one relationship, one instance of the
first entity is related to just one instance of the second entity
In a one-to-many relationship, one instance of the first entity is
related to many instances of the second entity, but each instance
of the second entity is related to only one instance of the first
entity In a many-to-many relationship, one instance of the second
entity is related to many instances of the second entity, and one
instance of the second entity is related to many instances of the
first 6 Slide 7 Editing Relationships Referential Integrity- a set
of rules Access enforces to maintain consistency between related
tables when you update data in a database. Cascade Delete When you
select this option, if you delete a record from one table,
corresponding records in the other table are also deleted Cascade 7
Slide 8 8 Slide 9 Types of Queries Select Query Queries that answer
a question Selects relevant data from database records Helps you
get just the data you need in a Datasheet view Append Query Adds a
record to the end of the table Works by selecting records from one
or more data sources and copying them to an existing table 9 Slide
10 Types of Queries Update Query Designed to change data in records
Often updates information in real time (think online purchases and
updating the on-hand amount of that item) Begins as a Select query,
then begins by clicking update Delete Query Deletes entire records
from a table Works similar to update query (must start with select
query) 10 Slide 11 Use Update or Delete? Type of queryWhen to use
itResults Use a delete queryTo remove entire records (rows) from a
table or from two related tables simultaneously. Delete queries
remove all the data in each field, including the key value that
makes a record unique Use an update queryTo delete individual field
values from a table. Makes it easier to delete values by updating
the existing values to either a null value (that is, no data) or a
zero-length string (a pair of double quotation marks with no space
between them). 11 Slide 12 12 Slide 13 Database Design Database
design concepts: Entities an entity is a tangible thing or an
event. It is a person, place, thing or concept about which data can
be collected. Consider the following examples: 1)The database of a
video store would have one entity named video and another named
customer (These are physical entities). 2)Organizations incur
expenses from paying hourly employees and purchasing materials from
suppliers. Hours worked and purchases are event entities in the
database of most organizations. 3)The library lends books for free.
If you were to think of checking out a book as a sales transaction
for zero revenue, how would you handle the revenue generating
event? The event entity here is the number of checkouts. 13 Slide
14 Database Design A book can have more than one author. An author
can write more than one book. How would you describe the
relationship between authors and books? Many-to-many A member can
borrow any number of books at one checkout. A book can be checked
out more than once. How would you describe the relationship between
books and checkouts? Many-to-many 14 Slide 15 Database Design
Attributes an attribute is a characteristic of an entity. These
attributes become the tables field. E.g. what are the attributes
for the entity Customer? Customer ID, First name, Surname, Date of
Birth, Address and Phone no. What are the attributes for the entity
Fashion Model? Name, Height, Weight, Dress size, Hair color and Eye
color. 15 Slide 16 Database Design Rules Rule 1: You do not need a
table for the business The database represents the entire business.
Thus in the practice example* The library is not an entity. Rule 2:
Identify the entities in the business description In our example
the entities are Members, employees and books. 16 Slide 17 Database
design rules Rule 3: Look for relationships among the entities
one-to-many, one-to-one, and many-to-many. In our example:
one-to-many: a member can check out more than one book. Rule 4:
Look for attributes of each entity and designate a primary key.
Attributes of members: name, DOB, phone no., email address, member
ID card number etc. Employees: name, # of hours worked, job
title,etc. Books: name, authors, type, status, member ID card
numberetc. Primary Key Foreign key 17 Slide 18 Database Design
Rules Rule 5: Avoid data redundancy you should not include extra
(redundant) fields in a table. Redundant fields take up extra disk
space and lead to data entry errors because the same value must be
entered in multiple tables. Rule 6: Do not include a field if it
can be calculated from other fields A calculated field is made
using the query generator as we will see later. 18 Slide 19
Metadata & Hierarchy of Data Metadata: Data about data.
Metadata describes how and when and by whom a particular set of
data was collected, and how the data is formatted. A text
document's metadata may contain information about how long the
document is, who the author is, when the document was written, and
a short summary of the document. Hierarchy of Data: refers to the
systematic organization of data, often in a hierarchical form. Data
organization involves fields, records, files and so on. 19 Slide 20
Data Dictionary Data Dictionary: In database management systems, a
file that defines the basic organization of a database. A data
dictionary contains a list of all files in the database, the number
of records in each file, and the names and types of each field.
Most database management systems keep the data dictionary hidden
from users to prevent them from accidentally destroying its
contents. Data dictionaries do not contain any actual data from the
database, only bookkeeping information for managing it. Without a
data dictionary, however, a database management system cannot
access data from the database. 20 Slide 21 Creating tables Create
tab Table design (in the tables group) Fill in the tables fields.
Choose a suitable data type for each field. For example text Last
Name Date/time Date Hired Yes/No US Citizen Change the lengths of
the text fields from 255 to 30 spaces. 21 Slide 22 Creating tables
We need to make the Employee ID a primary key: Select the Employee
ID field then in the Table tools Design click Primary Key tab After
you finish click the File tab Save object as then name your table
Note that this is different from Save Database as which saves the
whole database. 22 Slide 23 Creating Compound Primary Key The two
fields must be appear one after the other in the table definition
screen (plan ahead for that format). Highlight one field, hold down
the control key and highlight the next field. Go to table tools
design tab Primary Key 23 Slide 24 Adding records to a table Double
click the tables name in the navigation pane at the left of the
screen then start typing data directly into the cells. Enter your
data one field value at a time. Each time you finish entering a
value, press Enter to move the cursor to the next cell. After you
enter the data in the last cell in a row, the cursor moves to the
first cell in the next row and Access automatically saves the
record No need to save through the File tab. 24 Slide 25 Creating
Queries Using Calculated Fields in Queries: E.g. suppose we have
the following table. if you have an existing field containing the
number of boxes of Girl Scout cookies sold, you may want to see how
much money was collected for each cookie sale. In this example, the
boxes sold for $3.95 each. 25 Slide 26 Using Calculated Fields in
Queries In this case we will create a calculated field in a query.
Create tab Query design Dont Forget the Colon. Also the field name
must be enclosed in square brackets. 26 Slide 27 Using Calculated
Fields in Queries How to format the calculated field output? 1.
select the output column by clicking the line above the calculated
field expression. 2. the column darkens to indicate the selection.
3. Design tab property sheet format 27 Slide 28 Avoiding errors
when making calculated fields 1.Do not enter the expression in the
criteria cell. Enter it in the Field cell. 2.Spell, capitalize, and
space a fields name exactly as you did in the table definition.
3.Dont use parentheses or curly braces instead of the square
brackets. 28 Slide 29 Relating two or more tables by the join
operation Suppose you want to see the last names, employee IDs,
wage rates, salary status, and citizenship only for US citizens and
hourly workers. Problem: the data is spread across two tables.
Solution: add both tables and pull down the five fields you need.
Step 1: Create tab Query design Step 2: Click one table name and
hold down the ctrl button while choosing the other table name. Step
3: start pulling down the fields you need and add the criteria
expressions. 29 Slide 30 Relating two or more tables by the join
operation 30 Slide 31 Relating two or more tables by the join
operation you can use calculated fields using more than one table.
Just follow the same steps and add the calculated field in the
design view like what we did earlier. 31 Slide 32 Totals Queries
Assume that you want to see two pieces of information for hourly
workers: 1.The average wage rate 2.110 percent of the average rate
Step1: Create the first query, click the design tab Totals button
in the show/hide group. This will give us the average of the wage
rate field. Note that: you should type the revised heading for the
wage rate field, i.e. Average rate: wage rate. N.B. we need the
average of this field. Also to get the hourly workers only, enter
Criteria=No. 32 Slide 33 Totals Queries Now begin a new Query. But
instead of basing it on a table, we will base it on the previous
query. Design the new query and create a calculated field inside
it. 33 Slide 34 Update Queries Update Queries Suppose you want to
give all non-salaried workers a $0.50 pay raise. If you have 3
workers change the wage rate data in the table. If you have 3000
workers it would be much faster and more accurate to change the
wage rate by using an update query that adds $0.50 to each
non-salaried employees wage rate. 34 Slide 35 Update Queries Update
Queries First start by making a select query. Then click the update
button in the query type group. 35 Slide 36 Update Queries Update
Queries We will write the updated data in the Update to line in the
QBE grid. We will update only the non- salaried workers by using a
filter under the salaried field. 36 Slide 37 Update Queries Update
Queries When you run the query, the following warning message will
appear. Click yes, and the records will be updated. 37 Slide 38
Parameter Queries Suppose you want to know how many hours a
particular employee has worked. 1.Run a select query. 2.You will
get a message to enter the employee ID. Enter your employee ID and
you will get the desired information 38 Slide 39 Creating Reports
Create basic ungrouped report: Select the table create tab report
39 Slide 40 Creating Reports Create Grouped Report: Design tab
Group and Sort button in the grouping and tools group. Click the
Add group button then select the desired table (Employee ID) 40
Slide 41 Creating Reports To total the hours worked by each
employee: select the Hours column heading. Then on the Design tab
totals button in the grouping and totals group Sum Layout View 41
Slide 42 Creating Reports Design tab Report view from the views
group Report view (final view) 42 Slide 43 Small Quiz (Database
Concepts) The metadata for a database describes which of the
following properties of a database? It defines the fields in the
database tables It defines the structure of the database tables It
defines the sizes and formats of the fields in the database tables
It identifies the primary keys All of the answers provided are
correct 43 Slide 44 (Database Concepts) Because it is relatively
common and everyone has one, the date of birth is often used as a
primary key in a database table for identifying employees within a
corporation. True False (Database Concepts) What is the term for a
collection of related records, such as the scores for all of the
students in a given section of CIS300? Field Character Item Table
Query 44 Slide 45 (Database Concepts) Which of the following is the
smallest piece of data that can be stored within a database?
(select at least one, but no more than two answers) bit byte
character field record table 45 Slide 46 (Database Concepts) Which
of the following terms is often used to refer to the columns shown
in a database table? (select at least one, but no more than two
answers) row data element metadata field record data type 46 Slide
47 (Database Concepts) A field within a database is defined as a
single item of data that is common to all records and occurs as an
individual _____ within a table. cell column row value entry 47
Slide 48 (Microsoft Access) The Report Wizard is an easy to use
feature in Access that guides you through a series of questions and
then generates a customized report based on the answers you
provide. True False 48 Slide 49 (Microsoft Access) Which of the
following types of fields is used to produce a value from an
expression or function? Calculated AutoNumber OLE Object Indexed
Number 49 Slide 50 (Microsoft Access) Which of the following
objects provides a simple approach for less-experienced users to
extract information from a database? (select at least one, but no
more than two answers) Forms Macros Modules Queries Reports Tables
50 Slide 51 While a database itself is a collection of several
related files, the program used to build databases, populate them
with data, and manipulate the data is called a(n) _ DBMS Database
Management System. There are two overall approaches to maintaining
data: the traditional file approachwhich has no mechanism for
tagging, retrieving, and manipulating dataand the ____, which does
have this mechanism. Database Approach Data Approach Datafile
Approach Indexed file approach 51 Slide 52 52 Slide 53 53
