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C # tutorial
This chapter is about working with databases
In this chapter we will:
With Web Pages, you can easily display data from a database.
You can connect to an existing database, or create a new database from scratch.
In this example we will connect to an existing SQL Server Compact database.
In the "DemoWebPages" folder, create a new CSHTML file named "Products.cshtml".
Replace the code in the file with the code from the example below:
@{
var db = Database.Open("SmallBakery");
var selectQueryString = "SELECT * FROM Product ORDER BY Name";
}
<html>
<body>
<h1>Small Bakery Products</h1>
<table>
<tr>
<th>Id</th>
<th>Product</th>
<th>Description</th>
<th>Price</th>
</tr>
@foreach(var row in db.Query(selectQueryString))
{
<tr>
<td>@row.Id</td>
<td>@row.Name</td>
<td>@row.Description</td>
<td align="right">@row.Price</td>
</tr>
}
</table>
</body>
</html>
The Database.Open(name) method will connect to a database in two steps:
First, it searches the application's App_Data folder for a database that matches the name parameter without the file-name extension.
If no file is found, it looks for a "connection string" in the application's Web.config file.
(A connection string contains information about how to connect to a database. It can include a file path, or the name of an SQL database, with full user name and password)
This two-step search makes it possible to test the application with a local database, and run the application on a web host using a connection string.
| Method | Description |
|---|---|
| Database.Execute(SQLstatement [, parameters]) | Executes SQLstatement (with optional parameters) such as INSERT, DELETE, or UPDATE and returns a count of affected records. |
| Database.GetLastInsertId() | Returns the identity column from the most recently inserted row. |
| Database.Open(filename) Database.Open(connectionStringName) | Opens either the specified database file or the database specified using a named connection string from the Web.config file. |
| Database.OpenConnectionString(connectionString) | Opens a database using the connection string. (This contrasts with Database.Open, which uses a connection string name.) |
| Database.Query(SQLstatement[, parameters]) | Queries the database using SQLstatement (optionally passing parameters) and returns the results as a collection. |
| Database.QuerySingle(SQLstatement [, parameters]) | Executes SQLstatement (with optional parameters) and returns a single record. |
| Database.QueryValue(SQLstatement [, parameters]) | Executes SQLstatement (with optional parameters) and returns a single value. |