下拉列表中的SelectedIndexChanged在按钮的单击事件中未触发

问题描述

protected void Button1_Click(object sender, EventArgs e)
    {
        TableRow tb = new TableRow();
        TableCell tc=new TableCell();
        DropDownList db = new DropDownList();
        db.Items.Add("Bangalore");
        db.Items.Add("Mandya");
        db.Items.Add( "Hassan");
        tc.Controls.Add(db);
        tb.Controls.Add(tc);
        Table1.Controls.Add(tb);
        db.SelectedIndexChanged += db_SelectedIndexChanged;
        db.AutoPostBack = true;

    }
    private void db_SelectedIndexChanged(object sender,EventArgs e)
    {
       label.text="welcome";
    }

但是当我在页面加载事件db_SelectedIndexChanged执行中放置button_click的相同代码块时，将执行.
但是当我在Button中使用代码时，单击db_SelectedIndexChanged不会执行.

But when I place the same code block of button_click in page load event db_SelectedIndexChanged execute.
But when I use code in Button click db_SelectedIndexChanged doesn''t execute.

What may be the reason behind this?

推荐答案

protected void Button1_Click(object sender, EventArgs e)
    {
       db_SelectedIndexChanged(this, e);
    }

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