public DataSet GetData(List<int> idList) {

        System.Text.StringBuilder idXML = new System.Text.StringBuilder();

        // 把IdList转换成idxml（后面要用到的xml参数的值）

        foreach (var item in idList)

        {

            idXML.AppendFormat("<row><id>{0}</id></row>",item);

        }

        System.Text.StringBuilder strSql = new System.Text.StringBuilder();

        strSql.Append("select * from product where id in (");

        // 解析xml参数@a 取出ID 这里可以认为@a是一个特殊的表

        strSql.Append("select d.x.value('./id[1]','int') from @a.nodes('/*') as d(x)");

        strSql.Append(")");

        SqlConnection con = new SqlConnection("数据库连接字符串");

        SqlCommand cmd = new SqlCommand(strSql.ToString(), con);

        // 参数赋值

        SqlParameter[] para = new SqlParameter[]{

            new SqlParameter("@a",SqlDbType.Xml){Value= idXML.ToString()}

        };

        cmd.Parameters = para;

        // 查询

        SqlDataAdapter sda = new SqlDataAdapter(cmd);

        DataSet ds = new DataSet();

        sda.Fill(ds);

        return ds;

    }