Question

为什么我的代码在此代码块上显示语法错误

public string getPassword()
{
   DataClasses1DataContext myDbContext = new DataClasses1DataContext(dbPath);

   var password = (from user in myDbContext.Accounts
                   where user.accnt_User == txtUser.Text
                   select user.accnt_Pass).First();

   if (password == 0) 
   { }

   return password;
}

我想知道查询的结果是否为0，如果是0，我将关闭操作或类似的操作。但它一直显示错误我如何知道结果是否为0？如果您对我的方法有任何建议，请随意将其放入

Answer 1

如果没有返回数据，则调用.First()将导致异常......

如果没有数据

，调用.FirstOrDefault()将返回null

public string getPassword()
{
   DataClasses1DataContext myDbContext = new DataClasses1DataContext(dbPath);

   var password = (from user in myDbContext.Accounts
                   where user.accnt_User == txtUser.Text
                   select user.accnt_Pass).FirstOrDefault();

   if (password == null) 
   {
      // no data found - do whatever is needed in that case...
   }

   return password;
}

Linq-to-SQL查看是否没有结果

1 个答案: