mysql - MySql 连接器 C# 选择查询字符串 = 字符串

Question

我有一个查询 ，我知道@someStringValue 存在于表中， 但 MySqlDataReader 对象告诉我，查询不返回任何内容 ，哪里出错了？ C#代码：
SELECT * FROM db_tabel WHERE someStringField=\'@someStringValue\'

const string command = "SELECT * FROM `db_tabel` WHERE `varcharvalue`=\'@varcharvalue\'";
var connection = new MySqlConnection(_connectionString);
try
{
    connection.Open();
}
catch (Exception ex)
{
    Log.Error(ex.ToString());
    return null;
}
var cmd = new MySqlCommand(command, connection);
cmd.Parameters.AddWithValue("@varcharvalue",val );

MySqlDataReader reader;

try
{
    reader = cmd.ExecuteReader();
}
catch (Exception ex)
{
    connection.Close();
    Log.Error(ex.ToString());
    return null;
}
reader.Read();
if (reader.HasRows)
{
    var cl = GetInstanse(reader);
    reader.Close();
    connection.Close();
    return cl;
}
reader.Close();
connection.Close();
return null;