do-while in php resulting a non-stop page loading - php

Question

I want to have a $startdate counting 3 days backward from an input date by user, where those 3 days are not holidays.
So if the input date by user is October 22, the $startdate would be October 17 instead of October 19. Because October 19 and 20 are holidays
$i = 1;
do{
//some code to produce the $startdate
//...
//end
//check if $startdate is holiday or not
$this->db->where('hl_date',$startdate);
$query = $this->db->get('php_ms_holiday');
//if $startdate = holiday, it doesn't count
if($query->result_array()){
}
else{
$i++;
}
}while($i <= 3);
But, with that code I have a non-stop loading on the browser when a $startdate captured inside the if($query->result_array()) statement. And the browser can only returning results when I put something like this code below, inside the if($query->result_array()) statement:
$i = $i + n; //n is a number starting from 1, or
$i++;
but not:
$i = $i; //or
$i = $i + 0;
Why is that?

Answer 1

You just make a DB query which result interprets as TRUE. Maybe I wrong but it seems you are make the same db query in each loop iteration.
So, check your query, for example add specific date for holiday checking.

Answer 2

if($query->result_array()) will always evaluate to true, if your query is correctly formulated. So also if the number of rows returned is 0. This means that you never ever go to the else. You if-statement should check the number of results returned instead; Furthermore, I personally would prefer a normal for-loop:
for($i = 0; $i < 3)
{
//some code to produce the $startdate
//...
//end
//check if $startdate is holiday or not
$this->db->where('hl_date',$startdate);
$query = $this->db->get('php_ms_holiday');
//if $startdate = holiday, it doesn't count
if [num_rows equals 0] // test num_rows here; Not sure what your class offers here
{
$i++; // increment counter
// do whatever else you want to do
}
}

Answer 3

If this is always true:
if($query->result_array()){
}
Then this will always be true:
}while($i <= 3); //$i is never adjusted, so it will always be less than 3
Since you say that you want to display data from with the last 3 days but if there are holidays in between, you don't want to count them. To get around this I think you should not use the literal "3" since it can be adjusted, it should be a variable too.
A possible solution would be to have a variable such as:
$days_back = 3;
Then try to count the amount of holidays within the last 3 days(or something like that):
//You can make the holidays to be zero by default
$holidays = someWayToCountHolidays($startDate, $endDate); //You'll obviously have to code this
Then you can make make the variable your while loop will work agains
$num_days = $days_back + $holidays; //$holidays can be zero by default
Then something like below for you do while loop:
if($query->result_array()){
//Then do what ever you want to do here
} else {
//Then do what ever you want to do here
}
$i++; //Adjust $i
}while($i <= $num_days);