ASP.NET
Associazione dati

Origine dati SQL

I controlli che possono essere associati ai dati possono utilizzare i controlli SqlDataSource . Il controllo SqlDataSource consente non solo di recuperare i dati da un database, ma anche di modificare e ordinare i dati.

Recupero dati

Procedura memorizzata:

<asp:SqlDataSource ID="SqlDataSourceEmployees"
    runat="server"
    ConnectionString="<%$ ConnectionStrings:MyConnectionString %>"
    SelectCommand="sp_GetEmployees"
    SelectCommandType="StoredProcedure">
</asp:SqlDataSource>

Query SQL:

<asp:SqlDataSource ID="SqlDataSourceEmployees"
    runat="server"
    ConnectionString="<%$ ConnectionStrings:MyConnectionString %>"
    SelectCommand="SELECT
                       EmployeeID, 
                       EmployeeFirstName,
                       EmployeeLastName
                   FROM
                       dbo.Employees">
</asp:SqlDataSource>

parametri:

<asp:SqlDataSource ID="SqlDataSourceEmployees"
    runat="server"
    ConnectionString="<%$ ConnectionStrings:MyConnectionString %>"
    SelectCommand="SELECT
                       EmployeeID, 
                       EmployeeFirstName,
                       EmployeeLastName
                   FROM
                       dbo.Employees
                   WHERE
                       DepartmentID = @DepartmentID;">
    <SelectParameters>
        <asp:ControlParameter ControlID="ddlDepartment"
            Name="DepartmentID"
            PropertyName="SelectedValue" />
    </SelectParameters>
</asp:SqlDataSource>

Essere consapevoli dell'opzione CancelSelectOnNullParameter , che se impostato su true (predefinito) interromperà l'associazione dati se qualsiasi parametro è NULL

Uso di base

Vista a griglia:

<asp:GridView ID="GridViewEmployees"
    runat="server"
    AutoGenerateColumns="false"
    DataSourceID="SqlDataSourceEmployees">
    <Columns>
        <asp:BoundField DataField="EmployeeID" HeaderText="Employee ID" />
        <asp:BoundField DataField="EmployeeFirstName" HeaderText="First Name" />
        <asp:BoundField DataField="EmployeeLastName" HeaderText="Last Name" />
    </Columns>
</asp:GridView>

Oggetto origine dati

<asp:ObjectDataSource ID="ObjectDataSourceEmployees" runat="server"
    TypeName="MyPackage.MyDataAccessClass"                       
    DataObjectTypeName="MyPackage.Employee" 
    SelectMethod="GetEmployees"
    UpdateMethod="SaveEmployee"
    InsertMethod="SaveEmployee">
</asp:ObjectDataSource>

Nel codice sottostante

La classe di accesso ai dati

public class MyDataAccess
{
    public static List<Employee> GetEmployees()
    {
        List<Employee> results = new List<Employee>()
        {
            new Employee(){ Id=1, Name="John Smith" }, 
            new Employee(){ Id=2, Name="Mary Jane" } 
        };
    
        return results;
    }  

    public static void SaveEmployee(Employee e)
    {
        // Persist Employee e to the DB/cache etc. here
    }        
}

La classe dei dipendenti

public class Employee
{
    public Int32EmployeeId { get; set; }
    public string Name { get; set; }
}