c＃MySqlCommand似乎没有解析参数

Question

I'm trying to run a MySqlCommand with a parameter, but when I look in the SQL logs, the parameter is showing up.

I've tried with both @ and ?, tried with 'old syntax=yes' in my sqlconnection string also.

Here's my code.

bool CheckLoginDetails(string username, string password){
    DataTable dt = new DataTable ();
    MySqlCommand command = new MySqlCommand ("select * from `accounts` where `username` = '@username';", SL.Database.connection);
    command.Parameters.AddWithValue ("@username", username);
    dt.Load (command.ExecuteReader());
}

Here's the SQL logs.

150823  3:19:50    22 Connect   root@localhost on unity_test
       22 Query SHOW VARIABLES
       22 Query SHOW COLLATION
       22 Query SET character_set_results=NULL
       22 Init DB   unity_test
150823  3:19:52    22 Query select * from `accounts` where `username` = '@username'

I'm using .net 2.0 and I'm unsure of the mysql dll version, I found that here: http://forum.unity3d.com/threads/reading-database-and-or-spreadsheets.11466/

I'm unable to upgrade .net due to Unity. Any advice would be greatly appreciated!

Answer 1

Suggestion (not tested):

bool CheckLoginDetails(string username, string password){
    string sql = select * from accounts where username = ?";
    MySqlCommand command  = new MySqlCommand(sql);
    command.Parameters.Add(new MySqlParameter("", username));
    MySqlDataReader r = command.ExecuteReader();
    ...
}

The main point is that "?" should work.

Answer 2

Try command.Parameters.Add("@username", MysqlDbType.Varchar).Value = username;

Should work !

Answer 3

Try this, change

MySqlCommand command = new MySqlCommand ("select * from `accounts` where `username` = '@username';", SL.Database.connection);
command.Parameters.AddWithValue ("@username", username);

to

MySqlCommand command = new MySqlCommand ("select * from accounts where username = @username;", SL.Database.connection);
command.Parameters.Add("@username", username);

Answer 4

Try this(suggestion)

bool CheckLoginDetails(string username, string password){
DataTable dt = new DataTable ();
MySqlCommand command = new MySqlCommand ("select * from accounts where username = @username;", SL.Database.connection);
command.Parameters.AddWithValue ("@username", username);
dt.Load (command.ExecuteReader());

}