JavaFX MySQL database return sum - mysql

Question

I want to use datepicker to select range of dates. This range of dates is then queried in the database where the sum is counted...
My attempt:
public static int dateRange(){
int value = 0;
PreparedStatement stmt = null;
try {
Connection connection = DriverManager.getConnection("", "", "");
stmt = connection.prepareStatement("SELECT SUM(cost) FROM Items WHERE expiration_date between '" + Budget.datePicker1.getValue() + "' and '" + Budget.datePicker2.getValue() + "'");
ResultSet result = stmt.executeQuery();
result.next();
String sum = result.getString(1);
value = Integer.parseInt(sum);
} catch (Exception e){
value += 0;
}
return value;
}
It works. It returns the total if the days are there so to speak. If there are no days in the database as selected in the DatePicker then 0 pops up... But it looks messed up (catch block) and I was wondering if anyone could help me with an alternative solution?

Answer 1

First, since the value returned by the query is an integer value, there is no need to read it as a string and parse it. Just use result.getInt(...).
Second, if you are going to use a PreparedStatement, use it to properly set parameters, instead of building the query out of concatenated strings. Doing the latter exposes your application to SQL injection attacks.
If none of your dates are in range, then the SQL query will return NULL. Calling getInt() on column in a result set that is NULL will return 0, so you will get the result you want in that case anyway. If the previous value you got from a result set was SQL NULL, then calling result.wasNull() will return true, so if you really did need to handle that case separately, you could use that mechanism to do so.
You can do:
public static int dateRange(){
int value = 0;
// Use try-with-resources to make sure resources are released:
try (
Connection connection = DriverManager.getConnection("", "", "");
PreparedStatement stmt = connection.prepareStatement(
"SELECT SUM(cost) FROM Items WHERE expiration_date between ? and ?");
) {
stmt.setDate(1, Date.valueOf(Budget.datePicker1.getValue()));
stmt.setDate(2, Date.valueOf(Budget.datePicker2.getValue()));
ResultSet result = stmt.executeQuery();
result.next();
// Note that if there are no values in range, the SQL result will be NULL
// and getInt() will return 0 anyway.
value = result.getInt(1);
// however, if you need to explicitly check this and do something different
// if nothing is in range, do:
if (result.wasNull()) {
// nothing was in range...
}
} catch (SQLException e){
// this actually indicates something went wrong. Handle it properly.
Logger.getGlobal().log(Level.SEVERE, "Error accessing database", e);
// inform user there was a db error, etc...
}
return value;
}