Increment through date on week basis - php

Question

I am building a php application using pgsql as its back end.
I would like to increment the date by some amount of date shich should be loaded from my database which have given value as available=1,3,5(implying monday,wednesday,friday of a week).I would like to increment these available values to current date. I am using N format in date() function to represent the values of days in a week as 1 to 7 which is stored in available field in the database
If current date =22-07-2013 which is monday,then i have to increment this to wednesday(available=3) and then to friday(available=5) And then to monday of the next week.
And so on..
but i cant do that..
i am in need of such a code where the value of available may change according to the tuples in that tuple.So i would like to increment the current date based on the value of available.
So please help me to achieve it.
The code I used is attached herewith.Please have a look at it.
<?php
$sq = "SELECT * FROM $db->db_schema.dept where active='Y' and dept_id=$dept_id";
$result = $db->query($sq);
$ftime=$result[0]['f_time'];
$ttime=$result[0]['t_time'];
$a=date('Y-m-d').$ftime;
$b=date('Y-m-d').$ttime;
$to_time = strtotime("$b");
$from_time = strtotime("$a");
$minutes= round(abs($to_time - $from_time) / 60,2). " minute";
$days=array();
$days= explode("," , $result[0]['available']);
$result[0]['available'];
$intl=$result[0]['slot_interval'];
$slots=$minutes/$intl;
$dt1 =date("m/d/Y $ftime ");
$s_mnts=explode(":",$ftime);
$m= date('N');
-- $dt=array();
$a=$dt1;
$l=0;
for($n=1;$n<=3;$n++)
{
for($k=$m;$k<=7;$k++)
{ $l=$l+1;
if(in_array($m,$days))
{
echo "dasdsa";
echo date("Y-m-d H:i:s", strtotime("$a +$l days"));
echo"<br>";
}
$m=$m+1;
if($m==7){$m=1;}
}
}
?>
where
dept_id -> primary key of the table dept
$db->query($sq); -> query is used to fetch the given values and is defined in another file named database.php in the program folder.
f_time and t_time -> fields in the table dept which describes the from_time and to_time.f_time is the time from which we have to start increment and t_time is the time to end this increment.
Please inform me whether there is any improvement in the code I have given. .

Answer 1

What you could do is something like this:
You say how many days you want to increment. And give an array of availables.
<?php
$inicialDate = time(); //Timestamp of the date that you are based on
$tmpDate = $inicialDate; //Copy values for tmp var
$increment = 5; //Increment five days
$available = [1,3,5]; //Days available
/*Ok, now the logic*/
while($increment > 0){
$tmpDate = strtotime("+1 day", $tmpDate); //Increase tmpdate by one day
if(in_array(date("N",$tmpDate), $available){ //If this day is one of the availables
$increment--;
}
}
$finalDate = date("m/d/Y",$tmpDate);
?>
This logic should work, although I don't know how to reproduce it via a SQL Procedure.

Answer 2

From what I can tell, you are after something like
UPDATE sometable
SET some_date_column = some_date_column + ('1 day'::INTERVAL * some_integer_value);