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Introduction to Access 2007

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Click on the Access desktop icon or go to Start/All Programs/Microsoft Office/Microsoft Office Access 2007Click on Blank Database

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Enter a name for your database and either accept the default location or click on the folder to select a different location and then click the Create button

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Use the View drop-down menu to choose Design View

Enter a name for the table.

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Start entering fields for the Customer table. Start with a

CustomerID which will serve as a primary key.

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Data Types Help (obtained by clicking on the blue question in the upper right-hand corner of Access)

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Data Types Help (Cont.)

There is a drop-down list of choices for the Data Type

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Some Choices

• We have to select a Data Type for this field.

• We will select Text.

• Another possibility is AutoNumber – this choice guarantees uniqueness and is generated automatically, but it is also out of one’s control and can sometimes lead to problems/confusions (some people like it).

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After choosing a data type, enter a description.

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The key icon to the left of the field name indicates that this field will serve as the primary key (or part of it).

The larger key button above allows to make the field a primary key if it is not or to take away that status.

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Next change the Field Size to 7 and the Required to Yes and Allow Zero Length to No

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Enter other customer fields as shown

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To require or not to require

• One would certainly not require CustomerStreetAddress2, but one might consider setting the Require property of the other fields to Yes.

• Requiring a field can help ensure that the data is complete, but it can lead to some very unforgiving data entry scenarios.

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When adding a field for the customer’s phone number, we might want to use an Input Mask. Click in the Input Mask textbox and click the ellipsis (…) button that appears. You will be prompted to save the table.

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Select the Phone Number choice from the Input Mask list

of the Input Mask Wizard and click the Next button.

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The parentheses, space and hyphen appear automatically, the 9’s means that the area code is optional, the zero mean the rest of the numbers are required.

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Message I got because I did not supply all of the required numbers when entering an example in the Try it box.

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Decide how number will be stored.

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Finished mask from Wizard.

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Oops forgot the zipcode! Place the cursor in the PhoneNumber

row, right click and choose Insert Rows.

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Go through Input Mask Wizard to obtain Input Mask for a zipcode.

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Add a CustomerEmail field and click Save

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If we wanted to start entering Customer data, we would go

over to Datasheet view found under the View button.

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Datasheet view of Customer table

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Instead create an Order table by going to the Create tab

and clicking on the Table button.

Go to Design View and start designing an Order table, the first field is an OrderID – the primary key for the table.

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Foreign keys

• Next we establish the relationship “customer places order.” – This is a “one-to-many” relationship. One customer

may place many orders, but an order is placed by just one customer.

• This is done by making the next field on the Order table the ID of the Customer who has made the order.

• In the Customer table, CustomerID is a primary key, but here in the Order table it is known as a foreign key.

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Use the drop-down box in the Data Type area to select the

Lookup Wizard.

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One can use the Option 2 to provide a set of acceptable values, but in this case we want values from the Customer table.

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Later on we can look up the results of queries but at this

time we only have Tables. Go to Next.

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Use the arrow button to send over the CustomerID as well as CustomerLastName and CustomerFirstName

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While the data entry person is looking up a CustomerID, they will be looking at customer names, so let us put them in alphabetic order. Use the drop-down boxes to choose the appropriate fields.

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Note the Hide key column checkbox, the data entry person will see the customer name (and not the key) although they are looking up the key.

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Select a label for column in Order table. Click Finish.

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Using a Lookup is establishing a relationship and that the table involved in that relationship has to be saved before the relationship can be established. Click Yes.

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Add OrderShippingCost and OrderTotalCost fields. They should be of the Currency type.

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Calculated Fields?

• It may be that the OrderShippingCost or the OrderTotalCost can be calculated from other information stored about the order.

• And you might read somewhere that you should not store “calculated fields.” But there are at least two reasons not to follow that advice here.

1. Sheer convenience. These are important quantities that one wants to view readily without looking up all of the information required for the calculation.

2. The calculation might change but the customer pays based on the calculation made at the time of the order.

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Add OrderPaymentMethod field (could make should list of possibilities using Lookup Wizard) and OrderShipped field which will be of a Yes/No (Boolean) type.

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Shipping Address

• One could add fields for the shipping address and a yes/no field asking whether the shipping and customer addresses are the same.

• But a customer may place many orders all with the same shipping address which is different from the customer’s address. If the shipping address is in the Order table, the same address may have to be entered over and over.

• This is known as data redundancy and database design tries to minimize it.

• For now we will pretend the customer address and shipping address are the same until we are ready to address this issue.

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Add fields for when the order was placed and when it was shipped, these should be of the Date/Time type.

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Save the Order table and start designing an Item table. Note the ItemDescription is of the Memo type.

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The OrderLine or ItemLine or ItemInOrder Table• An order may contain many different items, an

item may be part of many different orders. Thus the order-item relationship is “many-to-many.”

• The many-to-many relationship is realized by having a separate table. (Our previous tables corresponded to entities.)

• If you had an order form, the data in this table would correspond to a single line on that form. Thus the table is often called the OrderLine or ItemLine table. If you want the table named after the relationship it is establishing, you might call it the ItemInOrder table.

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Start the new table, the first field in the table is a foreign key establishing the relationship to the Order table.

It cannot be a (simple) Primary key. Therefore, use the Primary Key toggle button to indicate that this field is not a primary key.

Change the field to Text, then switch to Lookup Wizrard.

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Unlike the customer lookup where we show the customer name but look up the ID, with order we will use just the ID. To finish off the Lookup Wizard, our new table must be saved.

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The second field is the ItemID, again use the Lookup Wizard – this time one can select both the ID and name fields.

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Multiple-field primary keys – composite key.

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Primary Key button

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Add ItemPrice and QuantityOrdered fields of Currency and Number types respectively. Because of sales, discounts, and changing prices, we place price in this table instead of in the Item table.

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We can get a picture of what we have accomplished so far by clicking on the Relationships button under the Database Tools tab .

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Relationships

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Cementing relationships

• The relationships between the tables came from using the Lookup Wizard.

• In DataSheet view, the user will be presented with a drop-down list of choices from the related table. However, at this stage the data entry person is free to enter a result that is not found in the other table.

• There is a way to insist that the foreign keys must match the primary keys of the related table.

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Right click on the line that represents the relationship and

choose Edit Relationship.

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Check the Enforce Referential Integrity checkbox if you want to insist that the foreign key must match a corresponding primary key. Click OK. Then the data entry person will get errors if this is not the case.

Would not allow because Customer table is open. Close it

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Close the Edit relationship dialog and then close the Customer table by right clicking and choosing Close.

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Return to Edit Relationship, choose Enforce referential integrity. The relationship is now shown in bold.