Java & SQL comparing dates

Question

I am trying to get client arrival date and compare it with my SQL database to see if in my data base the same date exists. however i receive the following error: The operator > is undefined for the argument type(s) java.lang.String, java.lang.String

P.S I need to compare it via java not using sql query

public void makeNewReservation() throws ParseException {
    // Enter informations

    System.out.println("Date of arrivel?");
    Scanner in = new Scanner(System.in);
    String date_entree = in.next();
    System.out.println("Date of exit? dd/MM/yyyy");
    String date_sortiee = in.next();
    calculateDaysDifference(date_sortiee, date_entree);



public  void calculateDaysDifference(String date_entree, String date_sortiee) throws ParseException{


ConnectionMySQL myConnection=new ConnectionMySQL();
    Connection conSQL=myConnection.startDBConnection();
    boolean connectionOK=myConnection.checkConnection(conSQL);

    String query = ("SELECT `START_DATE`,`END_DATE` FROM `room_booking");


    //if everything is fine with the connection, i try to execute a query
    if (connectionOK){
        try{
            ResultSet mesResultats=myConnection.executeQuery(conSQL, query);

            //the while loop is just for me to check the dates
            while (mesResultats.next()) {
                System.out.println("START_DATE: "+mesResultats.getString(1)+" END_DATE : "+ mesResultats.getString(2));


                if (date_entree > mesResultats.getString(1){
                    System.out.println("cant reserve room room reserved already");


                }
            }


            // je ferme la connexion
            conSQL.close();

        }

        catch(SQLException e){
            e.printStackTrace();


        }

    }

my data base

It's pretty straightforward. You have Strings. You're trying to compare them like numbers. Right here: ` if (date_entree > mesResultats.getString(1){` Either convert them, if that's what you want, or use String.Compare() — User1000547
– User1000547, Commented Feb 7, 2013 at 18:03
I'd store it as a DATE in the database, map the value into a java.util.Date, and compare that way. — duffymo
– duffymo, Commented Feb 7, 2013 at 18:07
the dates in my data base are stored as Date. but before I store the clients dates I must check if there is a room. then I will store them. — Batz
– Batz, Commented Feb 7, 2013 at 18:08

Bhavik Shah · Accepted Answer · 2013-02-07 18:27:33Z

4

You need to compare 2 Dates

1) Convert the input String into Date

SimpleDateFormat df=new SimpleDateFormat("yyyy-MM-dd");
java.util.Date d=df.format(/*date String*/);

NOTE: df.format will throw parseException if the String format does not match "yyyy-MM-dd" . I leave it upto you to make sure the date string is of the specified format.

2)get Date from sql query

java.util.Date sqlDate=new java.util.Date(resultset.getDate().getTime());

NOTE : resultset.getDate() will give you java.sql.Date class's object.

3) Compare 2 dates

edited Feb 7, 2013 at 18:27

answered Feb 7, 2013 at 18:22

Bhavik Shah

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Arpit · Accepted Answer · 2013-02-07 18:44:37Z

3

try this logic

Date date1=new Date(df.parse(mesResultats.getString(1)));
Date date2=new Date(df.parse(mesResultats.getString(2)));

int status=date1.compareTo(date2); //compareto is a function defined for date

if status==0 print same date
if status<0 print  date1 is older then date2
if status>0 print  date1 is newer then date2

[Update after comment] DateFormat df = new SimpleDateFormat("Format of your date goes here");

edited Feb 7, 2013 at 18:44

answered Feb 7, 2013 at 18:11

Arpit

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1 Comment

Batz Over a year ago

i am receiving the error msg: Cannot make a static reference to the non-static method parse(String) from the type DateFormat

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