C#中关于@的用法

string path = @"C:\Windows\"; // 如果不加 @,编译会提示无法识别的转义序列  
// 如果不加 @,可以写成如下  
string path2 = "C:\\Windows\\";  

string str = @"aaa=""bbb""";  
// 不加 @,可以写成  
string str2 = "aaa=\"bbb\""; 

string insert = @"  
insert into Users  
(  
UserID,  
Username,  
Email  
) values  
(  
@UserID,  
@Username,  
@Email  
)";  

string @operator = "+";  
string @class = "分类一";  
Console.WriteLine(@operator);  
Console.WriteLine(@class);  

string delete = "delete from Categery where CategoryID=@CategoryID";
SqlConnection connection = new SqlConnection("connectionString");
SqlCommand command = new SqlCommand(delete, connection);
command.Parameters.Add("@CategoryID", SqlDbType.BigInt);