您不应该在SQL中引用占位符.尝试将以下内容作为您的SQL字符串:

You shouldnt be quoting the placeholders in the SQL. Try the following as your SQL string:

$query = "INSERT INTO player_acct (username, salt, hashpass, email, state, country,  
          last_login) VALUES (:username, :salt, :hashpass, :email, :state, :country, :last_login)";