水晶报表传参问题，在线等解

[party620]

cs代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.Data.SqlClient;
using CrystalDecisions.CrystalReports.Engine;
using CrystalDecisions.Shared;

public partial class myCrpDataP : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }

    public DataTable GetSource()
    {
        using (SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=test;Integrated Security=True"))
        {
            string sql = "with testInfo as";
            sql += "(select CONVERT(char(7),edate,20) as mm,ccode,YEAR(Edate) as 'years' from Emergency)";
            sql += " select ccode,mm,cast(cast(100*count(*)/(select count(*) from emergency) as decimal(4,2)) as varchar)+'%' as radio ";
            sql += "from testInfo where years=@years";
            sql += " group by mm,ccode";

            SqlCommand cmd = new SqlCommand(sql, con);
            SqlDataAdapter myadapter =new SqlDataAdapter(sql, con);
            DataSet ds = new DataSet();
            myadapter.Fill(ds.Tables["Emercy"]);
            return ds.Tables["Emercy"];
            
        }
        
    }
    protected void btn1_Click(object sender, EventArgs e)
    {
        ParameterFields paramfields = new ParameterFields();
        ParameterField years = new ParameterField();
        years.Name = "years";
         //声明参数值
        ParameterDiscreteValue vYears = new ParameterDiscreteValue();
        //给参数赋值
        vYears.Value = ddl1.SelectedItem.Text;
        //将该参数添加到参数字段中
        paramfields.Add(years);

        CryReportP.ParameterFieldInfo = paramfields;  //将参数放入查看器控件中

        ReportDocument mydocument = new ReportDocument();
        mydocument.Load(Server.MapPath("CryReporPt.rpt"));  //加载报表
        DataTable dt = GetSource();
        mydocument.SetDataSource(dt);
        this.CryReportP.ReportSource = mydocument;   //设置数据源
    }
}

每次执行GetSource（）方法时都出错，myadapter.Fill(ds.Tables["Emercy"]);提示值不能为空
帮我看下如何修改代码？？

[party620]

以上代码有错，请看一下代码 执行以下代码，会出现必须声明变量@years 我不明白的是我在btn单击事件里不是已经声明过啦，并已经覆过值啦，为什么还会出现未声明变量 什么原因，我又该如何修改？？ 哦，更正之后的代码是

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.Data.SqlClient;
using CrystalDecisions.CrystalReports.Engine;
using CrystalDecisions.Shared;

public partial class myCrpDataP : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {

    }

    public DataTable GetSource()
    {
        using (SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=test;Integrated Security=True"))
        {
            string sql = "with testInfo as";
            sql += "(select CONVERT(char(7),edate,20) as mm,ccode,YEAR(Edate) as 'years' from Emergency)";
            sql += " select ccode,mm,cast(cast(100*count(*)/(select count(*) from emergency) as decimal(4,2)) as varchar)+'%' as radio ";
            sql += "from testInfo where years=@years";
            sql += " group by mm,ccode";

            SqlCommand cmd = new SqlCommand(sql, con);
            SqlDataAdapter myadapter =new SqlDataAdapter(sql, con);
            DataSet ds = new DataSet();
            myadapter.Fill(ds, "testEme");
            return ds.Tables["testEme"];
            
        }
        
    }
    protected void btn1_Click(object sender, EventArgs e)
    {
        ParameterFields paramfields = new ParameterFields();
        ParameterField years = new ParameterField();
        years.Name = "years";
         //声明参数值
        ParameterDiscreteValue vYears = new ParameterDiscreteValue();
        //给参数赋值
        vYears.Value = ddl1.SelectedItem.Text;
        //将该参数添加到参数字段中
        paramfields.Add(years);

        CryReportP.ParameterFieldInfo = paramfields;  //将参数放入查看器控件中

        ReportDocument mydocument = new ReportDocument();
        mydocument.Load(Server.MapPath("CryReporPt.rpt"));  //加载报表
        DataTable dt = GetSource();
        mydocument.SetDataSource(dt);
        this.CryReportP.ReportSource = mydocument;   //设置数据源
    }
}

[party620]

好吧，没人来