使用PHP如何从mysql检索多个日期范围并以日期数组形式返回

Question

Table in mySQL holds hotel reservations for next few years.

Each row contains id, start_date, end_date and status. the start_date contains a date type which represents the check-in date and the end_date is the checkout date.

I would like to retrieve an array of individual dates so that I can loop through one year calendar and display the dates for next year that are free and which are reserved.

Since the hotel can rent out the room again on the end_date since checkout is early, the end_date itself doesn't need to be included.

example

ID | start_date |  end_date  | status

1  | 03/15/2014 | 03/18/2014 |  Paid
2  | 05/22/2014 | 05/25/2014 |  Deposit
3  | 08/12/2014 | 08/13/2014 |  Paid

and to array:

 $months_arry = array(1 => '03/15/2014', 1 => '03/16/2014', 1 => '03/17/2014',
 1 => '05/22/2014', 1 => '05/23/2014', 1 => '05/24/2014', 1 => '08/12/2014');

Since all 12 months of the calendar are displayed vertically on the same page it would be easiest to just check each date against the array to know if it should be green for vacant or red for occupied.

In asp 3.0 on sql server i would have just created a record set rs with "

SELECT start_date, end_date from HotelBookings where start_date >= '2013-12-31'
 AND enddate <= '2015-01-01' ORDER BY start_date ASC"

then a .. do until rs.EOF loop .. inside the

loop i would retrieve the start_date and end_date and loop them until the two are equal while adding + 1 to the start_date while building the array of individual dates.

i found this example while looking for answer but it looks ugly and not elegant

<?php
// Make a MySQL Connection
$query = "SELECT * FROM example"; 

$result = mysql_query($query) or die(mysql_error());


while($row = mysql_fetch_array($result)){
    echo $row['name']. " - ". $row['age'];
    echo "<br />";
}
?>

Answer 1

Be careful with a loop that contains an SQL statement in its body, as the SQL will run n times, where n is the number of times the loop body executes. That's potentially quite inefficient.

The DateTime object can be your friend here.

// note that an array with the same key pointing to more than one value will have its values override eachother.
// array(1 => 'foo', 1 => 'bar') is generally not a good idea.
$months_array = array('03/15/2014', '03/16/2014', '03/17/2014', '05/22/2014', '05/23/2014', '05/24/2014', '08/12/2014');

// covert dates to check to DateTimes so that we can perform comparisons on them
$to_check_array = array_map(function ($value) { return new DateTime($value); } , $months_array);

// get all taken date ranges
$result = mysql_query("SELECT `start_date`, `end_date` FROM `date_table`");

// loop over all taken date ranges
while ($row = mysql_fetch_row($result))
{
  // convert dates to DateTimes to perform comparisons on them
  $start_date = new DateTime($row[0]);
  $end_date   = new DateTime($row[1]);

  // check each date against all taken ranges
  foreach ($to_check_array as $cur)
  {
    if ($cur >= $start_date and $cur < $end_date)
    {
      $taken = $cur->format('m/d/Y');
      echo "{$taken} is taken.<br>";
    }
  }
}

I think that should solve your problem. As for elegance, well, elegance is not exactly abundant in PHP. It's a language that's sort of been mish mashed together by many people from many backgrounds. It's a nice and simple, ever-evolving language, but not one I would call elegant. If you need to use PHP and are looking for some elegance in your web apps, I would recommend a framework like CodeIgniter or Laravel. The latter especially is quite elegant.

Also, be careful using the old mysql_ functions, as those are being removed from coming versions of PHP. You might want to look into mysqli or PDO.

Answer 2

Even though this isn't really the answer (and I won't mark it as one) here is how I solved the problem.

I was hoping there is a way to do this without having to do all these loop within loops and just to directly get the end result (an array of dates) from the mysql

This will select all date ranges from the mysql when the hotel room is booked and then convert the ranges to single dates in an array. So the end result is a unique sorted array of all dates after today's date when the hotel room has been reserved.

<?php
$current_date_t = date('Y-m-d');
$current_date = new DateTime($current_date_t);

// Make a MySQL Connection

$query = "SELECT from_date, to_date FROM t_booking_data where from_date >= '" . $current_date . "' ";

$result = mysql_query($query) or die(mysql_error());
$booked_days_array = array();

while ($row = mysql_fetch_array($result))
{
    $startDate_t = $row['from_date'];
    $startDate = new DateTime($startDate_t);
    $endDate_t = $row['to_date'];
    $endDate = new DateTime($endDate_t);

    while ($startDate < $endDate)
    {
        array_push($booked_days_array, $startDate->format('Y-m-d'));
        $startDate->modify('+1 day');
    }
}
$booked_days_array = array_unique($booked_days_array);
sort($booked_days_array);
?>