1. Week 2 Normalization and Queries
ISP 121
Week 2
Normalization and Queries

2. Normalization
The Old Car Club database presented a problem – what if one person owns multiple cars? (One owner can have many cars, so this is 1:M relationship)
Create a separate table for just the cars
How do you link the two tables together?

3. Normalization Example
Car Club (originally)
Member Name
Member Address
Member City
Member State
Member Zip
Member Phone
Dues Paid?
National Member?
Car Owned (repeats 1-n times)
Model of Car
Make of Car
Year of Car
Member ID (primary key)
Member Table
Name
Address
City
State
Zip
Phone
Dues Paid? National Member?
Member ID
Car Table
Model of Car
Make of Car
Year of Car
Member ID (not
a primary key here!)
Relationship
Primary Key in Member Table?
Foreign Key in Car Table?
1:M

4. Another Example Student Records Student ID (primary key) Student Info
Name
Address
City
State
Zip
Phone
Class Taken (repeats 1-n times)
Class Name
Grade
Number Credits
Major
Minor
Degree Sought
Student Info
Student ID
Name
Address
City
State
Zip
Phone
Major
Minor
Degree Sought
Grades
Class Name
Grade
Number Credits
Student ID
After
Let’s enter this one into Access and create
a few records of data.
Before

5. Why Relational? Eliminates redundancy Makes adding data easier
Allows for more secure access to only parts of the data

6. Simple Queries
To create an Access query, don’t use the query wizard. Instead, create query in Design view
Let’s see how Access does it

7. Queries
You can look for something after a certain date IF the data was stored as date/time and you say >1/1/2004
Dates should be entered with # before and after the date, and can be in many different formats, ie #1/1/2004#, #January 1, 2004#, #1-Jan-2004#

8. Queries
Logical OR - You can look for records in the state of Indiana or Illinois by saying “IL” OR “IN”
You can also say: In (“IL”, “IN”, “OH”)
Logical AND - you can make multiple entries in the query boxes. For example, in the State field enter “IL” and then in the Size field enter <3

9. Queries
Logical AND - You can also use an AND in one field. For example, in the Size field you can enter >=3 AND <=9
A slightly easier way of doing this is using the BETWEEN operator: Between 3 and 9

10. Parameter Query
What if you are looking for a person’s name in a database, but you don’t know the name until you run the query?
Use the built in parameter query
Form your query as usual, but in the Criteria box enter a prompt between square braces: [Enter your prompt here]

11. Queries That Calculate
When performing a query, you can aggregate the data
You can perform a Count, Sum, Avg, Max, Min, StDev, Var(iance), First, and Last
Count, First, and Last can be performed on types counter, number, currency, date/time, yes/no, text, memo, and OLE object
The others on counter, number, currency, date/time, and yes/no

12. Heights and weights database
Let’s look at a database of human heights and weights.
We’ll perform queries that aggregate data, that is, queries that compute such things as counts, averages, minimum values, and maximum values.
We’ll also group records.