how to make filter between two datebox zk

I have 2 datebox to make a filter. Their value will determine the 'from' and 'to' in my query (I'm using Oracle now), here is the code.

@Listen("onClick=#btnSaveFilter")
public void saveFilter() throws Exception {
    SimpleDateFormat formatter = new SimpleDateFormat("yyyy-MM-dd");

    c_main_filter.detach();
    cc.refreshFilter(""
            +"[Date of Birth] between '" + formatter.format(dbDateBirthFrom.getValue()).toString() + "' "
            + "and '" + formatter.format(dbDateBirthto.getValue()).toString() + "'");

}

when both datebox has value, the query work. but when they have no value the query is giving no data.

when datebox has value, it's giving data

"[Registration Date] between '2010-09-23' and '2010-09-23' "

when datebox has no value, it's giving no data

 "[Registration Date] between '' and '' "

like another filter I expect if the value is '' then all data will appear, but not :D hahaha. the condition is more than this actually, the filter has a lot of parameter one of them is this condition, and some of them use date format so there will be more condition like this.

do you know how to elegantly fix this problem, I've been thinking to use 'if' to determine the datebox has value or no then I will append the text to query text if both of them has value, but then I found another problem how I can add 'and' in query to give another condition,

let say I have 5 conditions so then

"select * from xxxx where 1stcondition and 2ndcondition and
3rdcondition and 4thcondition and 5th condition"

so when the dateboxes of the 5thcondition has no value the query will be wrong like this

"select * from xxxx where 1stcondition and 2ndcondition and 
3rdcondition and 4thcondition and"

if I want to use 'if' how can I play with the 'and'? but if you have alternative it will be great cause I don't have to deal with 'if' :D

Solution

You can use String.isEmpty() to determine whether you need to put an and:

String where = "";

if (from != null && to != null) {
    where += <yourDateCondition>;
}

if (<needToAddSecondCondtion>) {
    if (!where.isEmpty()) {
        where += " and ";
    }
    where += <secondCondition>;
}

// continue with other conditions

String query = "select * from xxxx where " + where;