Visual CSharp 2005 Express Edition (2006) [eng]

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you have the Database Explorer showing in the same area as the toolbox is displayed. One of the first things you will do when using the Database Explorer is either connect to an existing database or create a new database. Once connected to a database, you will have access to the various objects within the database. You can see an example of this in Figure 11-2.

Figure 11-2

Before actually connecting to a database yourself, take a look at some of the features in the Database Explorer.

Database Explorer Features

Within C# Express are a number tasks that can be handled within the Database Explorer. If you need to connect or work with a database when in the editor, you can use the Database Explorer to accomplish most of the tasks.

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The majority of the objects mentioned in this table were discussed in Chapter 10. You will be shown how to work with them further in the chapters that follow.

Working with Data Connections

To get started actually using the SQL Server tools within C# Express, you need to connect to a database. This can be a database that exists on your system or one provided with this book. There is a small database called CoffeeSQL.mdf that is provided in the Samples folder to which you can connect.

When a connection is achieved, you can then perform all the desired actions against the database, either working with database objects or going on to specify ways to use the database with your projects.

After starting C# Express, choose Tools Connect To Database. . . . This both opens the Database Explorer and starts the Add Connection dialog box.

In prior versions of SQL Server, databases were required to be already attached to a SQL Server instance. That is no longer the case; you can take a database that someone sends to you and connect to it using the Add Connection wizard. C# Express will create a connection to the database and utilize the SQL Server instance specified, in this case the SQL Express instance specified by default when you installed SQL Server Express.

The first page of the Add Connection dialog box is shown in Figure 11-3.

In the figure, you can see two options for security using the databases in SQL Server. For the purposes of this book, you will be using the default, which is Windows Authentication. You won’t have to worry about messing with security that way. When you click the Browse button, you can then locate the database file you want to connect to using a standard File Open dialog box.

Once you have located the database file you want to use, click Open, and the file path and name appears in the Add Connection wizard. Then click OK to open the Database Explorer. Now click the plus sign displayed next to the Data Connections label, and you see the database you choose. If you click the plus sign that appears next to the database, you will see all the object categories in the database, as shown in Figure 11-4.

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Figure 11-3

Figure 11-4

Okay, you have seen what it looks like to open a connection. It is time for you get busy and do it yourself.

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Try It Open Add a Database Connection to an Existing Database

If you have your own database you want to connect to, you can use that. Otherwise, as mentioned, you can use a database called CoffeeSQL.mdf that is located in the Samples folder in your folders for this book.

1.Open C# Express. Don’t open a solution at this point.

2.Choose Tools Connect To Database . . . . The Add Connection dialog box appears, along with the Database Explorer.

3.Click the Browse button. An open file dialog box with the title Select SQL Server Database File appears.

4.Locate the CoffeeSQL.mdf or whichever database file you want to connect to. You can see the CoffeeSQL.mdf file in Figure 11-5.

Figure 11-5

5.Click Open. The database file path and filename is now listed in the Database File Name field on the Add Connection dialog box.

6.Click OK. The connection is created, and you can browse to the database in the Database Explorer.

Creating a New Database Using the Add Connection Dialog Box

Creating a new database and a connection to that new database is just about as easy as connecting to an existing database. Of course, you still have the task of creating the objects such as tables that you want to use once the database is created. But the cool thing is you can do all of it from within C# Express.

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Instead of specifying an existing database in the open file dialog box, do the following:

1.Give a new name.

2.After giving the new name, click Open. The new name and the path you specified is displayed in the Add Connection dialog box.

3.Now, when you click OK, an additional dialog box opens that you will need to respond to.

The new dialog box displayed informs you that there isn’t an existing database file with that name and asks “Would you like to create it?” By responding and clicking Yes, C# Express then creates the database and then the connection to the database. The dialog box is shown in Figure 11-6.

Figure 11-6

Working with SQL Server Objects

Once you have created the data connection by either connecting to a current or a new database, you can then go into the database and start managing objects. The following sections walk through some of the objects you will use most often and how to use them.

Tables are the objects used the most in databases, and because they are actually the objects that hold the data, they are definitely the base place to start our discussion of the various SQL Server objects.

Table Definitions

As discussed in the previous chapter, tables are made up of columns and rows. When you are working in the design view of a table, you will be specifying properties for the various columns, such as last and first name. Depending on what you are trying to accomplish, there are a few ways you can work with tables in the Database Explorer. For example, if you just want to look at what columns are in a table and aren’t interested in knowing what the properties are, you can click the desired table, and then the columns will be displayed below the table title, as shown in Figure 11-7.

If you decide you want to see the properties of the columns or even want to edit (modify) a structure of a table, you just need to double-click on the table you are interested in. Once you have double-clicked the table, look at the structure of the table in the middle of the editor where files are normally displayed, with the column in the table listed above. In addition, a property window is displayed showing the properties of the columns. In the main properties window on the right, various properties are displayed for the table itself.

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Figure 11-7

In this Try It Out, you display a table’s structure and add a column to the table. So, with the CoffeeSQL database displayed in the Database Explorer:

1.Double-click the table called tblCustomers. As described, the table appears in the middle of the IDE, as shown in Figure 11-8.

Figure 11-8

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2.Place the cursor in the blank field under Customer Name.

3.Type EmailName for the Column Name; then press Enter.

4.In the Data Type drop-down list, pick NVarChar(50), as shown in Figure 11-9.

Figure 11-9

5.Save the file by choosing File Save All.

Once you have saved the table information, you can now view the data.

Note that there are a lot of properties you need to set when are first creating a table, such as indexes and default values. The purpose of this book at this point is to get you started in using C# Express with SQL Server Express. Creating databases and tables from scratch can take entire chapters, so I will let you read up on some of those items on your own and show you how to use some of the tools that you have available.

Viewing Table Data in C# Express

To view the data in the tblCustomers table, right-click the table and choose Show Table Data. The data is displayed in a data sheet, or grid, format. You can then modify the data as desired. Generally you use this mode to correct or test tables in the database.

One important thing to know at this time is that you can move around the records using controls at the bottom of the screen. You can see this screen in Figure 11-10.

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Figure 11-10

Notice that the new column is included and is set to NULL. The NULL value means that a field has not been set and the system does not know what type of value is in there.

There is a powerful toolbar also displayed in Figure 11-11, where one of the choices is Change Type. This toolbar gives you the ability to change the results set you are looking at into a query that is either a type view (selectable data) or a stored procedure (bulk updating), depending on what you want to do with it.

1.Right-click the tblCustomers table.

2.Pick Show Table Data from the menu. The table appears in the main pane of the C# Express IDE, as shown in Figure 11-10.

Other SQL Server Objects

There are many other SQL Server objects that you can work with from the Database Solutions, such as views and stored procedures. While more detail is beyond the scope of this text, there are some good books out there that provide more information about creating these objects.

You can also work with views in the IDE, as shown in Figure 11-11. The figure shows a view being created, where you can see the table it’s based on as well as the grid of fields to use. Lastly, you can see the result on the bottom of the screen.

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Figure 11-11

You will also learn about some of these features as you continue through the next couple of chapters on learning about data controls and using ADO.NET in your C# applications.

Summar y

Microsoft has gone to a great extent to give you the ability to use C# Express to create usable applications without necessarily having to use full-blown versions of Visual Studio 2005 and SQL Server. In fact, to help with this, they have included a scaled-down version of SQL Server with C# Express called SQL Server Express. Formally known as the MSDE, this version provides developer with the ability to use SQL Server on a smaller scale for development purposes or even as single-user solutions. They have even gone as far as to provide the ability to point and connect to a SQL Server database file with the extension of .mdf.

While SQL Server Express has tools to working with SQL Server databases, C# Express also provides a number of tools for allowing you to connect to SQL Server Databases and maintaining them right from within the C# Express IDE using the Database Explorer. With the Database Explorer you can modify the various objects found with databases such as tables, views, and stored procedures.

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Exercises

1.What does MSDE stand for?

2.What are the two main tools provided in SQL Server Express?

3.Which tool do you use in C# Express to work with databases in and out of projects?

4.What is the difference between a view and a stored procedure?

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