Comparing date from variable to MySQL date - php

Question

I'm comparing date specified in PHP with dates in MySQL table and then echoing all rows with dates after the date in PHP. It works OK when I specify the date in the SELECT command, but when I make it a variable it doesn't work.
My PHP is:
$sql = "SELECT event FROM LifeEvents WHERE event_date > '1995-02-27'";
$result = $conn->query($sql);
if ($result->num_rows > 0) {
// output data of each row
while($row = $result->fetch_assoc()) {
echo $row["event"] . "<br>";
}
} else {
echo "0 results";
}
$conn->close();
This works ok. But when I replace the SELECT with:
SELECT event FROM LifeEvents WHERE event_date > $date
It no longer works.
For the variable I've tried working with both:
$date = new DateTime('1995-02-27')
and
$date = '1995-02-27'
Neither of them works. The data type in MySQL is DATE.

Answer 1

For the string variable
$date = '1995-02-27'
$sql = "SELECT event FROM LifeEvents WHERE event_date > '$date'";
// this should work exactly as
$sql = "SELECT event FROM LifeEvents WHERE event_date > '1995-02-27'";
For the DateTime object, this should work
$date = new DateTime('1995-02-27')
$sql = "SELECT event FROM LifeEvents WHERE event_date > '" . $date->format(Y-m-d). "'";
I suggest you always set the timezone when you are dealing with dates and times because underestimate timezones can result in really bad bugs specially if your applications is dealing with many timezones and you have timestamp data type in your database.
make it a habit to do this
define('DEFAULT_TIMEZONE','UTC');//set this in your global config.php file
$date = new DateTime('2000-01-01', new DateTimeZone(DEFAULT_TIMEZONE));

Answer 2

Lets create a variable that holds a date and then convert it to date format that MySQL can understand.
$dt = date('Y-m-d', strtotime('1995-02-27')); // maybe filled dynamically
$sql = "SELECT event FROM LifeEvents WHERE event_date > '$dt'";
$result = $conn->query($sql);
if ($result->num_rows > 0) {
// output data of each row
while($row = $result->fetch_assoc()) {
echo $row["event"] . "<br>";
}
} else {
echo "0 results";
}
$conn->close();
Then change what you want in order to serve your needs.
Hope I pushed you further.

Answer 3

That's because '1995-02-27' and DateTime('1995-02-27') are both not valid in that case :
'1995-02-27' would work if you'd have put extra quotes around $date in your SQL query : "SELECT event FROM LifeEvents WHERE event_date > '$date'"
DateTime('1995-02-27') doesn't have a __toString() magic method so PHP is unable to represent it as a string. You have to use the format method : $date = $date->format('Y-m-d') (and it will still miss the quotes)
One or another solution, you need to protect yourself against SQL injections using prepared statements! And you will actually no longer need any quote.

Answer 4

Try using the Carbon library for PHP.
Store a date with PHP:
$current_time = Carbon::now()->toDateTimeString();
Then just compare it the same way.