实体框架:'SqlParameter已被另一个SqlParameterCollection包含'

Question

我正在尝试执行下面的代码.我的目标是检查是否存在任何具有给定电子邮件ID的用户.

var result = userDbContext.users.SqlQuery("SELECT * FROM USERS WHERE @email='@emailValue'",
new SqlParameter("@email", "email"),
new SqlParameter("@emailValue","abc@mail.com"));
//new SqlParameter("p1", existingUser.password));

if (result.Count() == 0) //getting exception here
{
    ViewBag.comment = "Sorry. We can not find your credentials";
    return View();
}

但我得到例外,result.count()不知道出了什么问题.

例外情况是:

"SqlParameter已被另一个SqlParameterCollection包含"

我怎么解决这个问题？

Answer 1

您只需要在 Sql 查询之后添加 ToList() 方法并删除 SqlParameter 中的@：

var result = userDbContext.users.SqlQuery("SELECT * FROM USERS WHERE 
@email=@emailValue",
new SqlParameter("email", "email"),
new SqlParameter("emailValue","abc@mail.com")).ToList();
//new SqlParameter("p1", existingUser.password));

if (result.Count() == 0) //getting exception here
{
    ViewBag.comment = "Sorry. We can not find your credentials";
    return View();
}

它会起作用。

Answer 2

你可以试试这个

var check = (from item in userDbContext.users where item.email == email select item).FirstOrDefault();
if (check == null)
{
    ViewBag.comment = "Sorry. We can not find your credentials";
    return View();
}