c#后台一般处理程序中把变量的值拼成json格式字符串

//一般处理程序代码string login_name = context.Request["login_name"].Trim();
BLLS data = new BLLS();
string select_id = "select use_id from sq_sgxhcom.fru_users where use_name=@p0";
int use_id = Convert.ToInt32(data.Select(select_id, login_name).Tables[0].Rows[0][0]);
string aa = "select use_name,use_realname from sq_sgxhcom.fru_users where use_id=@p0";
string name = data.Select(aa, use_id).Tables[0].Rows[0][0].ToString();
string realname = data.Select(aa, use_id).Tables[0].Rows[0][1].ToString();
string ccc = "select use_name,use_realname from sq_sgxhcom.fru_users where use_id=8";
string name1 = data.Select(ccc).Tables[0].Rows[0][0].ToString();
string realname1 = data.Select(aa, use_id).Tables[0].Rows[0][1].ToString();
string aaa = " [<K>\"name\":\"{0}\",\"realname\":\"{1}\"</K>,<K>\"name\":\"{2}\",\"realname\":\"{3}\"</K>]";//将数据拼成json字符串格式
returnstr = string.Format(aaa, name, realname,name1,realname1).Replace("<K>", "{").Replace("</K>","}");
context.Response.Write(returnstr);

//js代码
$.ajax({
type: "post",
url: "ajax/staff_manag.ashx?type=obtain_count",
data: {
login_type: login_type,
login_name: login_name
},
async: true,
dataType: "json",
success: function fun(json) {
alert("我是"+json[0].name+"和"+json[1].name+"是好朋友");
}
});