Introduction to Microsoft Access 2003

Mr. A. Craig Dixon

CIS 100: Introduction to Computers

Spring 2006

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Why Access 2003?

• Microsoft Access is used to structure and store information that will be updated often and / or will be searched by one or more specific criteria.

• Common personal uses include storing information about collections (movies, sports cards, etc.)

• Common corporate uses include storing sales information, employee data, etc.

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What is a Database?

• Microsoft Access is used for creating a special data structure called a database.

• A database is a collection of data stored in tables.• Tables consist of records, which are themselves

collections of data about a single item.• Each datum in a record is called a field.

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You Define the Structure

• Because of the wide variety of data people store in databases, a database initially has no tables, and thus no fields or records.

• The user must create one or more tables and must further define the structure of each table by defining the number and types of fields in the table.

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An Example of a Database

• Suppose you want to build a database of movies.• You might want to define a table with fields for the movie’s title,

rating, and year of release. You might also define fields for the actors in the movie or the production company that produced it.

• After defining the structure of this table, you enter information about each movie as a separate record.

• If you want to build a larger database, you could include another table of information about different actors• Fields in this table might include the actor’s age, hometown, etc.

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Database Keys

• Each table must contain a primary key; each record in the table must have a unique value in the primary key field.• In databases involving people, the most common key is

the person’s social security number.• It is sometimes desirable to use more than one

field as the key; this is called using a composite key.• In the movie example, you might want to define year of

release and title as a composite key, since movies are sometimes re-released in different years.

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Field Data Types

• Each field must be given a data type based on what kind of data the field will contain. There are several data types, including:• Text – any kind of alphanumeric data; like Excel labels, no math

functions can be performed on text data.• Number – integer or floating-point numerical data on which math

operations need to be performed. Even data like ZIP codes should be of text data type, since no math operations are performed on them.

• Yes/No – the only valid entries are Yes and No• AutoNumber – each record is assigned the next consecutive number,

beginning at 0. This is most useful for primary keys• OLE object – many kinds of external content, including sounds, pictures,

and documents, can also be stored in an Access database using this data type.

• Clearly, a great deal of planning is involved before constructing a database.

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Creating a Database in Access

• Upon starting Access, the user must first create a database.• The user is immediately prompted to save the database.

This is because, unlike other programs in the Microsoft Office suite, Access saves changes to the database contents as soon as they are made.

• Only changes to the design of the database itself must be explicitly saved.

• After saving the new database, the user is prompted to create a new table using one of three methods. The method we will use is Design view.

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Anatomy of Design View

Field name

Data type Field description

Default valuebox

Requiredbox

Field size box

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Relationships

• The user can link two tables using an arrangement called a relationship.

• In a relationship, the value of a field in one table exactly matches the primary key of a record in another field. This value is called a foreign key.• In the movie example, instead of entering the actor’s

name in the field for the star of the movie, you would instead enter the primary key value of the specific actor from the actors table.

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Garbage In, Garbage Out

• Databases are built around the principle of garbage in, garbage out (GIGO).

• This means that databases are extremely dependant on consistency in formatting of the data in them.• Even subtle variations like upper-case and lower-case

letters can make huge differences in how a database will respond.

• For this reason, there are numerous controls to ensure that data is input in a consistent manner.

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Structured Query Language (SQL)

• Databases are often quite large and complex, which makes finding specific data challenging.

• To make the task less daunting, databases provide a feature called querying.

• The user creates a request, called a query, that describes what data he or she wants displayed and how to display it.

• When the query is run, it creates a presentation of data called a view.• All queries are written in a language called Structured Query

Language (SQL, pronounced SEE – kwul). Some people refer to SQL as Standard Query Language. The two are interchangeable.

• Anything that can be done to a database (creating or deleting a table, adding or deleting a record, changing a value, etc.) can be done using a query.

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A SQL Example

• Say you have a database of movies. You want to find all the movies in the database that are in the comedy genre and were released between 1988 and 1998. The SQL query might look like this (SQL keywords are in all caps):

SELECT movieName FROM movies WHERE genre=“Comedy” AND releaseYear > 1987 AND releaseYear < 1999;

• This is a relatively simple query; most will be significantly more complex than this!

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Access Makes it Easy

• Learning basic SQL takes weeks; learning SQL well takes years. We don’t have weeks or years to learn it.

• Fortunately, Microsoft Access provides another way.

• We can create queries in a drag-and-drop interface using the Select Query feature of Access.

• Queries created using the Select Query feature are still in SQL; Access just hides the messy details.

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Anatomy of Select QueryAvailable tables

Available fields

Fieldinformation

Sorting criteria Query criteria

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A Simple View

• To create a simple view, just drag the fields you want in the view into separate field boxes in the Select Query window.

• Once you run the query, your view is created.

Run the query

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A Sorted View

• There are two methods of sorting:• Ascending – least to greatest (numeric) or alphabetically (textual)• Descending – greatest to least (numeric) or reverse alphabetically

(textual)

Run the query

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Multiple Ordering

• You can sort on more than one field by putting the field that defines the primary ordering in the left-most column, the secondary ordering in the next slot, etc.

Run the query

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A View With a Criterion

• Sometimes you want to see only data that meets a certain criterion. To do this, just enter the criterion in the criteria field.

• This query returns records where Wage is less than 15.

Run the query

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A View Using Boolean NOT

• Instead of a positive criterion, you can use a negative criterion by using the Boolean operator NOT.

• This query returns all records where PositionTitle is not “Cook”.

Run the query

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A View Using Boolean OR

• You can create a query that returns records that meet one criterion or the other by adding all the criteria in the “or:” blank(s).

Run the query

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A View Using Boolean AND

• You can create a query to return data that meet all of several criteria by entering several criteria on the same line of the criteria field. (You can use the same field more than once.)

Run the query

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Forms and Reports• Datasheet view often is not the most attractive way to view

or edit your data. Access provides two features commonly used to make these tasks more user-friendly.• Forms – allow the user to create a GUI front-end for the

database where data can be entered, modified, and deleted.• Reports – allow the user to create stylized printouts of data

from the database. Reports can be based on a table or a queried view.

• Most high-level programmers will use other, more specialized tools for these tasks, but for beginning students, they are a powerful extension to Access.

• We will create simple forms and reports in our in-class project.