Microsoft Visual C# 2005 Express Edition: Build a Program Now! (31 page)

TO CREATE A DATABASE USING VISUAL C# 2005 EXPRESS EDITION

The .mdf file extension is used

by the SQL Server family of prod-

ucts. The .mdf contains the entire

In the Add New Item dialog box, select
SQL

1 Start
Visual C# 2005 Express Edition
.

4

database; this means all tables and

Database
from the Visual Studio Installed

other elements that can exist in

Templates. Type in the filename
CarTracker.mdf

the database are located in that

Create a new Windows application and name

and click the
Add
button. By doing so, you’ll create

one file. The only thing that is

2

not part of the .mdf file is the log

it
CarTracker
.

a database and attach the database file (
CarTracker.

information, which is in a .ldf file.

mdf
) to your CarTracker project.

It is created whenever you create

the database. The file has an .ldf

You will now create the database that will hold

3

extension and is used to store the

all the tables for the application. In the

You will then see a Data Source Configuration

5

database log information. You

Solution Explorer, right-click the
CarTracker
project,

Wizard. Don’t pay attention to this dialog box

can see this file by clicking the

select
Add
, and then select
New Item
.

just yet; you’ll learn about it soon. Just click
Cancel

Show All Files icon in the Solution

Explore
r
.

for now.

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The Solution Explorer should now contain a new item within

6 your project: the new database file called
CarTracker.mdf
as

shown in Figure 8-3.

You will now start to add tables to your database. To do this,

7 you can either double-click the
CarTracker.mdf
file or rightclick
CarTracker.mdf
and then select
Open
. This will cause Visual Studio to connect to the SQL Server 2005 Express instance

installed on your machine.

The Database Explorer should appear on the left side of the

screen where the toolbox usually opens up, as shown in Figure 8-4.

Figure 8-3

Solution Explorer with the newly cre-

If you do not see the Database Explorer, go to the View menu, Other

ated CarTracker.mdf database file

Windows, Database Explorer.

Under the database name, you should see a list of database elements represented by folder icons. Although you will not recognize most of them, you will see two elements that are already familiar to you: the database diagram and the tables. You will use both of these elements shortly. You’ll know that you’re connected to the database when you see the database icon with an electric cord

Figure 8-4

Database Explorer with the CarTracker

look-alike. When you’re disconnected, you will see the database icon with a red X. However, seeing a red X

database connected

does not necessarily mean that you’re disconnected. You might have been disconnected earlier, but the Database Explorer was never refreshed. To verify the state of the connection to your database, you should click the
Refresh
button in the Database Explorer toolbar.

Right-click on your database named
CarTracker.mdf
in

8 the Database Explorer and select
Close Connection
. You

should now see the red X near your database name.

You’re now disconnected. To reconnect, you can do three different things. You can double-click your database name (e.g.,
CarTracker.mdf
) in the Database Explorer, you can click the

Refresh button, or you can right-click on the filename in the

Database Explorer and select
Modify Connection. . .
. If you

select the Modify Connection route, you will see a dialog box

like the one shown in Figure 8-5.

Figure 8-5

The Modify Connection dialog box will let you

reconnect to your CarTracker database

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Because it’s a good practice to test your connection, you can click the Test Connection button and it 9 will verify the connection currently specified. It’s also verifying that SQL Server 2005 Express Edition is ready and able to receive connections from your

One thing you should pay

applications.

Currently, you have only one database in your projects,

attention to in this dialog box

but it’s not unusual to need to connect to and get

is the Database Filename.

information from two or more databases. That’s why

Because you didn’t save any

10 Click
OK
to reconnect to your database.

Database Connections in the Database Explorer is there

as a tree, for it’s representing each database as a node

files, everything is still located

in that tree. You have only one node in the tree, which

in a temporary folder identified

is your CarTracker database.

by the content of the text box.

As soon as you save all of the

Creating Tables in Your Database

files in your project, the data-

base will be saved along with

Now you’ll create all tables and relationships needed for the CarTracker application. Using
the other project files, wherever

the information found in Figure 8-2, you’ll create tables, primary keys, identities, and
they are located. You can later

foreign key relationships in the CarTracker database, and you’ll do all of this without leaving
verify that location by going

Visual Studio.

to the Tools menu, selecting

Options. . . , and then looking

at the Projects and Solutions

TO CREATE TABLES IN A DATABASE

node in the tree. On the right

panel in this dialog box, you

Let’s start with the Color table. In the Database Explorer, right-click on the table’s folder icon and 1

can determine where your proj-

select
Add New Table
. You should now see an empty grid on the designer surface, which is called
ects are stored by looking at

the Table Designer. You will also see that a new toolbar has appeared, which is called the Table Designer toolbar. This toolbar has all the tools necessary to help you create a table without writing a single SQL

the first text box called Visual

query.

Studio Project Locations.

You’ll now add a column to the Color table. Type
ColorID
in the Column Name field of the Table 2 Designer. Select
int
as the Data Type and uncheck the
Allow Nulls
check box because this column will be the primary key in this table. A primary key cannot be null since it is part of the uniqueness of a row in the table.

Before you add the second column in the Color table, you’ll set this column as the primary key. To do

3 so, you need to click the
Set Primary Key
icon in the Table Designer toolbar.
From this point onward, for every

tree control and every control that

is a group (i.e., has a + sign), the

The database diagram shown in Figure 8-2 illustrates that you also need this column to be an identity;
word
expand
will be used instead

therefore, you need to modify that property in the Column Properties window right below the Table
of repeating the words
click on the

Designer. Scroll down until you see the Identity Specification group. Click on the
plus sign
(+) located to

+ sign
.

the left of the words
Identity Specification
to expand this group. Now click in the
(Is Identity)
field and set it to
Yes
. Leave both the Identity Seed and Identity Increment set at 1 for now.
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