我有一个项目，其中需要在第一次点击时触发事件，但在第一次点击时不会触发事件，在第二次点击时会触发它，但在第一次点击时确实会发生回发，但不会触发事件
<asp:Button ID="btn_search" runat="server" Text="Search" CssClass="button blue" onclick="btn_search_Click" CausesValidation="False"/>
按钮点击事件的cs代码
protected void btn_search_Click(object sender, EventArgs e)
{
if (txt_subcategory.Text.Length != 0 && txt_category.Text.Length == 0 && txt_author.Text.Length == 0 && txt_publisher.Text.Length == 0 && txt_isbn.Text.Length == 0 && txt_bookname.Text.Length == 0 && txt_edition.Text.Length == 0)
{
btnsearchsubcat();
txt_subcategory.Text = "";
}
else if (txt_subcategory.Text.Length == 0 && txt_category.Text.Length != 0 && txt_author.Text.Length == 0 && txt_publisher.Text.Length == 0 && txt_isbn.Text.Length == 0 && txt_bookname.Text.Length == 0 && txt_edition.Text.Length == 0)
{
btnsearchcat();
txt_category.Text = "";
}
else if (txt_subcategory.Text.Length == 0 && txt_category.Text.Length == 0 && txt_author.Text.Length != 0 && txt_publisher.Text.Length == 0 && txt_isbn.Text.Length == 0 && txt_bookname.Text.Length == 0 && txt_edition.Text.Length == 0)
{
btnsearchauthor();
txt_author.Text = "";
}
else if (txt_subcategory.Text.Length == 0 && txt_category.Text.Length == 0 && txt_author.Text.Length == 0 && txt_publisher.Text.Length != 0 && txt_isbn.Text.Length == 0 && txt_bookname.Text.Length == 0 && txt_edition.Text.Length == 0)
{
btnsearchpublisher();
txt_publisher.Text = "";
}
else if (txt_subcategory.Text.Length == 0 && txt_category.Text.Length == 0 && txt_author.Text.Length == 0 && txt_publisher.Text.Length == 0 && txt_isbn.Text.Length != 0 && txt_bookname.Text.Length == 0 && txt_edition.Text.Length == 0)
{
btnsearchisbn();
txt_isbn.Text = "";
}
else if (txt_subcategory.Text.Length != 0 && txt_category.Text.Length == 0 && txt_author.Text.Length == 0 && txt_publisher.Text.Length == 0 && txt_isbn.Text.Length == 0 && txt_bookname.Text.Length != 0 && txt_edition.Text.Length == 0)
{
btnsearchname();
txt_bookname.Text = "";
}
else if (txt_subcategory.Text.Length != 0 && txt_category.Text.Length != 0 && txt_author.Text.Length == 0 && txt_publisher.Text.Length == 0 && txt_isbn.Text.Length == 0 && txt_bookname.Text.Length == 0 && txt_edition.Text.Length == 0)
{
btnsearchcatsubcat();
}
else if (txt_subcategory.Text.Length != 0 && txt_category.Text.Length != 0 && txt_author.Text.Length != 0 && txt_publisher.Text.Length == 0 && txt_isbn.Text.Length == 0 && txt_bookname.Text.Length == 0 && txt_edition.Text.Length == 0)
{
btnsearchcatsubcatauthor();
}
else if (txt_subcategory.Text.Length == 0 && txt_category.Text.Length == 0 && txt_author.Text.Length == 0 && txt_publisher.Text.Length == 0 && txt_isbn.Text.Length == 0 && txt_bookname.Text.Length != 0 && txt_edition.Text.Length != 0)
{
btnsearchbooknameedition();
}
else if (txt_subcategory.Text.Length != 0 && txt_category.Text.Length == 0 && txt_author.Text.Length != 0 && txt_publisher.Text.Length == 0 && txt_isbn.Text.Length == 0 && txt_bookname.Text.Length == 0 && txt_edition.Text.Length == 0)
{
btnsearchsubcatauthor();
}
else if (txt_subcategory.Text.Length != 0 && txt_category.Text.Length == 0 && txt_author.Text.Length == 0 && txt_publisher.Text.Length != 0 && txt_isbn.Text.Length == 0 && txt_bookname.Text.Length == 0 && txt_edition.Text.Length == 0)
{
fillgridsubcatpublisher();
}
else if (txt_subcategory.Text.Length == 0 && txt_category.Text.Length == 0 && txt_author.Text.Length == 0 && txt_publisher.Text.Length == 0 && txt_isbn.Text.Length == 0 && txt_bookname.Text.Length != 0 && txt_edition.Text.Length == 0)
{
btnsearchname();
}
else
{
Page.ClientScript.RegisterStartupScript(this.GetType(),
Guid.NewGuid().ToString
(), "<script language=JavaScript>alert('Fill The TextBox ');</script>");
}
}