LSP 121Week 1

Intro to Databases

Welcome to LSP 121• Quantitative Reasoning and Technological Literacy II• Continuation of quantitative data concepts from LSP 120

• We will spend three weeks storing and retrieving data using a database

• Given a data set, what is its mean, median, standard deviation and more (descriptive statistics)?

• Given two sets of data, is there a correlation?

Welcome to LSP 121• Continuation of quantitative reasoning concepts from LSP

120• Given a set of data, can we calculate probability and

risk?• How do we manipulate data, compress it, or check for

errors - algorithms• If you feel you know this material, take the test• Let’s get started!

Are Databases Important?• Virtually every major area of study in college and in the

real world needs to store and retrieve data• Commerce (sales, marketing, production, management, …)• Education (daily operations, research, …)• Healthcare• Government

• Do you really want to enter the workforce and not know what a database is and how they are created?

Why a Database (and not a spreadsheet)?

• You have too many separate files or too much data in a single file

• You need to look at the data in many different ways• You need to share the data• You want to secure access to the data and control data

values

Basic Terms• Table – an object you define and use to store data. Each

table contains information about a particular subject, such as customers, patients, or orders

• Fields – tables contain fields (columns) such as first name, street address, score

• Record – a logical collection of fields• Query – an object that provides a custom view of data

from one or more tables

Field Attributes (Data Types) You want to create fields for Name, Address,

Telephone, Amount Paid,… Text – the most common! Number – do NOT use unless you plan to do

arithmetic with this field Date/Time Currency – use with money fields AutoNumber – similar to Number but Access

automatically inserts the numbers for you Yes/No (and others)

What is a Primary Key? Most tables should have a primary key, but it is

optional A primary key is a field that can uniquely identify

every record For example, your student ID is a primary key in

a lot of databases here at DePaul (every student ID is unique – no duplicates)

Social Security number primary key for a lot of government databases

If you are searching for a particular record, you can use the primary key

What is an Index?• You can make any field an index• An index also let’s you search for one or more records

• An index can require unique values (like the primary key) but an index can also allow duplicate values

• You can search a database on any field, but the search will be faster if you make the field an index

Table Example• Let’s create a table for the following:

• Home address / phone book

* What is the primary key?

* What are the indexes?

Let’s Practice• Let’s run the program Access and create a simple table

and then enter some data for the example Home Address Phone Book (Smith, Jones, Anderson, Abbott) (in Oak Park, Chicago)

• Did you correctly assign the type for each field? Did you select the field as an index? Did you create a primary key?

Queries• Let try a couple queries• Don’t use the Query Wizard – we’ll design our own

queries• What is Smith’s phone number?• Show all people living in Oak Park• ???

• STOP. Let’s do Activity 1.

Importing Data into a “Flat” Access Database

• Many times you want to take an existing data set and “import” it into an Access database

• The existing data set can be plain text (.txt), a spreadsheet (.xls), or other forms of existing databases

• Let’s consider the example of importing a spreadsheet into an Access database

Importing Spreadsheet Data• Create a new (blank) database (unless you are importing

into an existing database, then simply open that one)• Select External Data from the top tabs• Select the appropriate type of file that you want to import

Importing Spreadsheet Data• You probably want to import the data into a new table• If the spreadsheet you are importing has more than one

worksheet, select the appropriate worksheet• Does the first row contain column headings?

Importing Spreadsheet Data• Now you can tell the wizard which fields should be

indexed in the new table• Choose your own primary key or let Access add a primary

key?• Give the table a name and click on Finish• You may have import errors – check the file

xx$_ImportErrors

Importing Spreadsheet Data• Let’s try an example – we will import the data in

spreadsheet Presidents.xls• Open the QRC website and copy the file Presidents.xls to

either My Documents or the Desktop (may not be able to copy to Desktop)

• Run Access and perform the import operation on the Master worksheet

• Try a FIND or two• Try a FILTER or two

Finding a Record• A very simple way to look for a record• But you can only search in one table, and you can only

look for one field• Open the table, then on the Home tab click on Find (or

CTRL-F)• Enter values as necessary• Wildcard character: *• Find is nowhere near as powerful as performing a query

(later)• We’ll try FINDing a record in a few moments

Filtering Records• If you want to see all the rows in a table that match any

part of a value, you can use the Filter command• A couple different forms of Filter. Let’s look at Filter by

Selection• Open the table you want to filter. Highlight the field you

want to filter on. Then on the Home tab click on Selection• To undo filtering, click on Toggle Filter• We’ll try filtering in a few moments

Further Questions• How does Google work?

• Should Google restrict its searching capabilities to comply with a government?

• What is data mining?

• STOP. Now do Activity 2.