java.sql.SQLException: Invalid value for getInt() - ‘id‘ Query: select ‘id‘, ‘username‘

java.sql.SQLException: Invalid value for getInt() - ‘id’ Query: select ‘id’, ‘username’, ‘password’, ‘email’ from t_user where username =?

原SQL语句
String sql =“insert into t_user(‘username’, ‘password’, ‘email’) values(?,?,?)”;

改为
String sql = “insert into t_user(username,password,email) values(?,?,?)”;

单引号的原因。