Manual De C Sharp

How to Create a Database with SQL Server Express
To create your database, launch your C# .NET software. Start a new Windows project by clicking File > New Project. Call it anything you like, because we won't be using this form. But without SQL Server Management Studio Express installed, you need a new Windows Application to create a SQL Server Express database.
From the menu bars at the top ofC# .NET, click Project. From the Project menu, select Add New Item:
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When you click on Add New Item, you should see the following dialogue box appear (we've chopped a few templates out for convenience sake):
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However, for later versions of C# you'll see this instead:
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Select Service-based database (or SQL Database for older versions).
Give your database a name. Call itMyWorkers.mdf. We'll create a database of fictitious people who work for us, and give them job descriptions.
Click the Add button. In C# 2010 you're then asked to choose a Database model. Leave it on the default of Dataset and click Next. In earlier versions of C#, you'll see the following:
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Select Tables, and then Finish. (The Dataset is important, and you'll see how they work later).
In C#2010, you'll see this:
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Just click Finish to return to the C# design environment.
In all C# versions, it may seem as though nothing has happened. But take a look at the Solution Explorer on the right and you'll see that your database has been added to your project:
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However, your database is empty at the moment. We need to add a table to it. So right click on MyWorkers.mdf. From themenu that appears, click Open.
You should see the Database Explorer appear:
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Right click on Tables to see the following menu:
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Select Add New Table from the menu, and a new table will appear in your main window:
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The Columns are all the Columns that you want in your table. The idea is that you type a Name for the Column, and then specify what kind of data (Data Type) you wantto go in it, such as text, numbers, Yes/No values, etc. Allow Nulls means, "Does this column need to be filled in?" For example, if you had a middle name column then this will often be left blank, because not everybody has a middle name. In which case that particular column can have Nulls. If you need the data, such as an Identifying Number, then you leave the Allow Nulls box unchecked.
We'llcreated a very simple table with just four columns:
Worker_ID
first_Name
last_Name
job_Title
The first Column, Worker_ID, will be a number. We can let the database itself handle this. Every time a new worker is added, SQL Server Express will then take care of assigning a new number for that worker. This is known as Auto Increment in other databases, such as Access.
So type Worker_ID underColumn Name and your screen will look like this:
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The next thing to do is tell SQL Server Express what kind of data is going in to the Worker_ID column. Click inside of Data Type and you'll see it's a dropdown list of options:
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As you can see, there's an awful lot of them! Select int from the list, though. Leave the Allow Null box unchecked, and your screen will look like this:
[pic]One more thing to do with this Column. Have a look at the bottom of your screen and you'll see a list of Properties. The one we want is Identity Specification. Set Is Identity to Yes, and Identity Increment and Identity Seed will appear:
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By setting these values, SQL Server Express will add 1 to the Worker_ID column when we add a new worker.
Click under Column Name and type the second of ourtable fields:
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For the Data Type, select nvarchar(50). The varchar is short for variable-length character string. With nvarchar, the n is short for Unicode, and the data will be stored in the UTF-16 format. Use nvarchar if you're going to be storing non-English characters. Otherwise, use varchar. The same is true of all the n's on the list.
Check the Allow Nulls box and your new Column...