Question

I have one ‘Log‘ entity which contains information about temperature.
I’m trying to build a report which have two fields only:

quantity : this field will tell how much my search should look
interval : minutes, hours, days, months, years (this field tells me how much is the interval of the search

This is my Log entity:

public class Log implements Serializable {
    private static final long serialVersionUID = 1L;

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private Integer id;

    private Timestamp time;

    private String value;
    // getters and setters ...

So when the user inform like 1 minute I should look for the last minute (or 60 records at least).

Or if 1 month I should get all the data from the last month.

I’m trying something like this:

log.time < CURRENT_TIMESTAMP AND log.time > :param

But how can I specify to minutes, hours ? What I mean is how can be more specific in my query ?

Answer 1

If the time unit is “days”:

Calendar now = Calendar.getInstance();
now.add(Calendar.DAY_OF_MONTH, -quantity);
Date param = now.getTime();

Keep your query as is, and bind param to the :param request parameter.

For other intervals, do the same, but with the appropriate Calendar field (HOUR_OF_DAY, MINUTE, etc.) instead of Calendar.DAY_OF_MONTH.