从数据库中的不同表中检索数据以发送要执行的SQL代码，并返回数据？

Question

I am making a class in Java to connect and otherwise talk to a database, that I have set up elsewhere. I want to use the executeQuery method for a statement, and recieve a ResultSet, from where I will retrieve the information received in the ResultSet.

My issue is with the SQL command, as in; the query I'm sending to the database. Something appears to be wrong, and I get an SQLException at the very point where I send the command, meaning I must have done something wrong. Maybe I'm writing something wrong? I can't tell, since I've simply tried to follow the example guidance provided for this course the best way I can.

Here is the query I'm trying to send:

"SELECT fr.DepartureLocation, fr.Destination, d.Date, d.Time FROM `FlightRoute` fr,
`Departure` d WHERE d.FlightRouteId = fr.Id AND d.Date > " + dateFrom + " AND
d.Date < " + dateTo + " AND fr.Destination = `" + destination + "`;"

The "dateFrom", "dateTo" and "destination" are all parameters for the method I'm calling, and I'm trying to limit the results I get from this statement, to those within a certain date-span as well as having a specific destination. I might add that the dates are integers lined up such as this: 20131205 This should make it so that later dates are a higher number.

Is the way that I use the parameters with the SQL code wrong somehow, or did I make generally faulty SQL code here?

Thanks a lot, to anyone who might be able to provide a correct SQL code for me to use, so that I may see what I did wrong (since I'll have to make a few more similarly working SQL statements)! Thanks in advance! :)

EDIT: Here is the requested code where I am announcing the query and trying to execute it:

try
{
    ArrayList<Departure> departures = new ArrayList<>();
    Statement stmt = con.createStatement();
    System.out.println("derp0");
    String query = "SELECT fr.DepartureLocation, fr.Destination, d.Date, d.Time FROM FlightRoute fr, Departure d WHERE d.FlightRouteId = fr.Id AND d.Date > " + dateFrom + " AND d.Date < " + dateTo + " AND fr.Destination = `" + destination + "`;";
    System.out.println("derp0.1");
    ResultSet rs = stmt.executeQuery(query);
    System.out.println("derp1");

As a short explaination, the souts are to check where the SQLException occured, and I can only say that the exception happens right after "derp0.1".

Answer 1

I suggest the following change:

PreparedStatement ps = connection.prepareStatement(
  "SELECT fr.DepartureLocation, fr.Destination, d.Date, d.Time FROM `FlightRoute` fr,"+
  "`Departure` d WHERE d.FlightRouteId = fr.Id AND d.Date > ? AND d.Date < ? "+
  " AND fr.Destination = ?");

ps.setDate(1, dateFrom);
ps.setDate(2, dateTo);
ps.setString(3, destination); //assuming destination is a String 

ResultSet rs = ps.executeQuery();

In JDBC you should always use parametrisation, as above. It might also solve your problem, which could be caused by an invalid date format.