Question

I have a table in MySQL server called Caller_List. In this table I have a single date column called call_date whose data type is Date. I have created a web page in which I have a SELECT Box for from_day (where all days 1 to 31 are stored), a SELECT box for month (where all month names from January to December are stored), a SELECT box for year (where all years from 2000 to 2012 are stored. Like I also have a SELECT box for to_day, to_month and to_year.

The problem is when I fetch these day,month and year from java servlet using request.getParameter() method, it is fetched as string data type and stored in variable called from_date and to_date. I concatenate from_day,from_month and from_year and store in the variable called from_date. Also I concatenate to_day,to_month and to_year and store in to_date. I concatenate them in the format year-month-day since MySQL understands this format.

I then pass the following query to retrieve data between these two from_date and two date:

select caller_name,call_date 
from Caller_List 
where call_date>='"+from_date+"' and call_date<='"+to_date+"'

I also tried the following query but in vain:

select caller_name,call_date 
from Caller_List 
where call_date between '"+from_date+"' and '"+to_date+"'

I also came to know that I need to convert from_date and to_date to date format before executing the query. But I am a novice in java, I do not know how to do it. Also I want the date in the format year-month-date. I do want to display time with date, please please help me!

Answer 1

If you only want to know how to parse a String to a Date in java, you could simplely use the SimpleDateFormat class.

final DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
try {
    final Date fromDate = dateFormat.parse(from_date);
} catch (ParseException e) {
    // ...
}

Assume that your from_date string is looks like 2012-09-16.

And if you want to display a date with time. You can also use the SimpleDateFormat.

final DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss");
try {
    final String displayDate = dateFormat.format(new Date());
} catch (ParseException e) {
    // ...
}

The displayDate should looks like 2012-09-16 20:13:25.

One more thing, you could compare a string type and a date type in MySQL. Just make sure your date string has the pattern “yyyy-mm-dd hh:mm:ss”. Of course, you should use the preparedStatement.