<p>I need to get the first and last day of a month in the format YYYY-MM-DD given only the month and year. Is there a good, easy way to do this?</p>

First day is always YYYY-MM-01, isn't it? Example:
```
date("Y-M-d", mktime(0, 0, 0, 8, 1, 2008))
```
Last day is the previous day of the next month's first day:
```
```
$date = new DateTime("2008-09-01");
$date->modify("-1 day");
echo $date->format("Y-m-d");
```
```