ASP.NET Web Pages - Databases






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ASP.NET Web Pages - Databases



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This chapter is about working with databases.





What We Will Do


In this chapter we will:



  • Create a web page to list data from a database




Displaying Data from Database



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.




Adding a Customers Page


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:




Products.cshtml



@{
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>

Run example »



Example Explained



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.







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ASP.NET Database Object Reference





































MethodDescription
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.





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