如何将变量传递给SqlDataSource的SelectCommand？

Question

我想将变量从后面的代码传递给SqlDataSource的SelectCommand？

我不想使用内置参数类型(如ControlParemeter,QueryStringParameter等)

我需要通过一个可变的？

以下示例不起作用

<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:itematConnectionString %>" SelectCommand = "SELECT items.name, items.id FROM items INNER JOIN users_items ON items.id = users_items.id WHERE (users_items.user_id = @userId) ORDER BY users_items.date DESC" >
    <SelectParameters>
        <asp:Parameter  DefaultValue="<%= userId %>" Name="userId"  DbType="Guid" />
    </SelectParameters>
</asp:SqlDataSource>

Answer 1

你总是可以在后面的代码中这样做:

<asp:SqlDataSource ID="SqlDataSource1" runat="server" 
    ConnectionString="<%$ ConnectionStrings:itematConnectionString %>">

编辑

试试这个,删除SelectCommand属性和SelectParameters:

SqlDataSource1.SelectParameters.Add("userId", userId.ToString());

SqlDataSource1.SelectCommand = "SELECT items.name, items.id FROM items INNER JOIN users_items ON items.id = users_items.id WHERE (users_items.user_id = @userId) ORDER BY users_items.date DESC"

然后在后面的代码中执行此操作:

<asp:SqlDataSource ID="SqlDataSource1" runat="server" 
    ConnectionString="<%$ ConnectionStrings:itematConnectionString %>"
    SelectCommand = "SELECT items.name, items.id FROM items INNER JOIN users_items ON items.id = users_items.id WHERE (users_items.user_id = @userId) ORDER BY users_items.date DESC"></asp:SqlDataSource>


SqlDataSource1.SelectParameters.Add("userid", DbType.Guid, userId.ToString());

这对我有用,这也有效:

<asp:SqlDataSource ID="SqlDataSource1" runat="server" 
    ConnectionString="<%$ ConnectionStrings:itematConnectionString %>">

Answer 2

我们必须经常这样做,所以我做了我所谓的DelegateParameter类

using System;
using System.Collections.Generic;
using System.Text;
using System.Web.UI.WebControls;
using System.Reflection;

namespace MyControls
{
    public delegate object EvaluateParameterEventHandler(object sender, EventArgs e);

    public class DelegateParameter : Parameter
    {
        private System.Web.UI.Control _parent;
        public System.Web.UI.Control Parent
        {
            get { return _parent; }
            set { _parent = value; }
        }

        private event EvaluateParameterEventHandler _evaluateParameter;
        public event EvaluateParameterEventHandler EvaluateParameter
        {
            add { _evaluateParameter += value; }
            remove { _evaluateParameter -= value; }
        }

        protected override object Evaluate(System.Web.HttpContext context, System.Web.UI.Control control)
        {
            return _evaluateParameter(this, EventArgs.Empty);
        }
    }
}

将此类放在app_code中(如果将其放在那里,则删除命名空间)或在自定义控件程序集中.在web.config中注册控件后,您应该能够执行此操作

<asp:SqlDataSource ID="SqlDataSource1" runat="server" 
    ConnectionString="<%$ ConnectionStrings:itematConnectionString %>"
    SelectCommand = "SELECT items.name, items.id FROM items INNER JOIN users_items ON items.id = users_items.id WHERE (users_items.user_id = @userId) ORDER BY users_items.date DESC">
    <SelectParameters>
    <asp:DelegateParameter Name="userId"  DbType="Guid" OnEvaluate="GetUserID" />
    </SelectParameters>
</asp:SqlDataSource>

然后在你背后的代码中实现你喜欢的GetUserID.

protected object GetUserID(object sender, EventArgs e)
{
  return userId;
}

Answer 3

只需在页面中添加一个自定义属性即可返回您选择的变量.然后,您可以使用内置的"control"参数类型.

在后面的代码中,添加:

Dim MyVariable as Long


ReadOnly Property MyCustomProperty As Long
    Get
        Return MyVariable
    End Get
End Property

在select parameters部分中添加:

<asp:ControlParameter ControlID="__Page" Name="MyParameter" 
PropertyName="MyCustomProperty" Type="Int32" />

Answer 4

附加到GUID:

 SqlDataSource1.SelectParameters.Add("userId",  System.Data.DbType.Guid, userID);

Answer 5

您可以使用 asp:SqlDataSource 内置的 OnSelecting 参数

示例：[.aspx 文件]

<asp:SqlDataSource ID="SqldsExample" runat="server"
SelectCommand="SELECT [SomeColumn], [AnotherColumn] 
               FROM [SomeTable]
               WHERE [Dynamic_Variable_Column] = @DynamicVariable"
OnSelecting="SqldsExample_Selecting">
<SelectParameters>
    <asp:Parameter Name="DynamicVariable" Type="String"/>
</SelectParameters>

然后在后面的代码中实现 OnSelecting 方法：[.aspx.cs]

protected void SqldsExample_Selecting(object sender, SqlDataSourceCommandEventArgs e)
{
     e.Command.Parameters["@DynamicVariable"].Value = (whatever value you want);
}

您还可以将其用于其他类型的数据库操作，只需实现您自己的方法：

OnInserting="SqldsExample_Inserting"
OnUpdating="SqldsExample_Updating"
OnDeleting="SqldsExample_Deleting"