ORDER_BY date LIMIT 1 [duplicate] - php

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SQL order by date, time [duplicate]
Closed 9 years ago.
I have table named notify with (seeker, donor, date) columns
the date column of type (datetime) and it stores the following format YYYY-MM-DD HH:MM:SS I'm trying to SELECT 1 record with the latest date from notify table and then compare the date with the current date and calculate the number of days between tow dates..
<?php
session_start();
$email = $_GET['email'];
date_default_timezone_set('Asia/Riyadh');
$time = date("Y-m-d H:i:s");
$note = "SELECT * FROM notify WHERE seeker='".$_SESSION['email']."'AND donor='".$email."' ORDER_BY `date` DESC LIMIT 1";
$st = $conn->prepare($note);
$st->execute();
if($found = $st->fetch(PDO::FETCH_ASSOC)){
$now = $time;
$old_date = strtotime($found['date']);
$dateif = $now - $old_date;
if(floor($dateif/(60*60*24)) >= 7){
echo "the difference between tow dates is 7 days or more";
} else { echo "difference between tow dates is less than 7 days";}
}
?>
the code is not working ! i have only one record in my notify table with this value in date 2013-04-22 09:15:47

Answer 1

First of all, you should use prepared statements like this:
$note = "SELECT *
FROM notify
WHERE seeker=:seeker AND donor=:donor
ORDER BY `date` DESC
LIMIT 1";
$st = $conn->prepare($note);
$st->execute(array(
':seeker' => $_SESSION['email'],
':donor' => $email,
);
Without the place holders you're still open to SQL injection.
Second, you can't compare a string with an integer in this way:
$now = $time; // string
$old_date = strtotime($found['date']); // integer
$dateif = $now - $old_date; // dunno?
You should compare apples with apples:
$seven_days_ago = strtotime('-7 days');
$old_date = strtotime($found['date']);
if ($old_date > $seven_days_ago) {
echo "difference between tow dates is less than 7 days";
} else {
echo "the difference between tow dates is 7 days or more";
}

Answer 2

Since your date column doesn't exist, there's no point in ordering by it. Also, you're exposed to SQL injection in the case where $_SESSION['email'] is not secured.
So, the correct form would be to use prepared statements, as well as order by the right column. (assuming PDO, you can use mysqli as well):
/** #var PDO $pdo - Assuming a PDO connection. */
$query = "SELECT * FROM `user` WHERE `ID` = :email ORDER BY `time` DESC";
$stmt = $pdo->prepare($query);
$stmt->execute(array($_SESSION['email']));
$result = $stmt->fetchAll(PDO::FETCH_ASSOC); //Get all results in an associated array form.

Answer 3

Jack's answer shows you how to use prepared statements correctly. Here is the code to simplify the date calculation using DATEDIFF().
$note = "SELECT *, DATEDIFF(NOW(), `date`) AS date_diff
FROM notify
WHERE seeker=:seeker AND donor=:donor
ORDER_BY `date` DESC
LIMIT 1";
$st = $conn->prepare($note);
$st->execute(array(
':seeker' => $_SESSION['email'],
':donor' => $email,
);
$row = $st->fetch(PDO::FETCH_ASSOC);
// do something with $row

Answer 4

If you are attching any variables to string then you need to concatinate them using dot and oder by will come after where condition and inside $_SESSION you missed quotes
$query = "SELECT * FROM user WHERE ID='".$_SESSION['email']."' ORDER_BY date, time";

Answer 5

For retrieving latest date from database please try executing following sql query
$query="SELECT * FROM user WHERE ID='".mysql_real_escape_string($_SESSION[email])."' ORDER_BY date,time desc limit 1";

Answer 6

In order to retrieve latest date you need to sort field for date in descending order
$note = "SELECT * FROM notify WHERE seeker=' ".$_SESSION['email']. " ' AND donor=' ".$email." ' ORDER_BY date DESC LIMIT 1";

Answer 7

have you try to order by desc? as shown bellow:
$note = "SELECT * FROM notify
WHERE
seeker=' ".$_SESSION['email']. " '
AND
donor=' ".$email." ' ORDER_BY date DESC LIMIT 1";

Answer 8

you forgot ` here around date. date is reserved word in mysql,
if you want to use it as column name place ` around it.
EDIT also you have extra space remove it
$note = "SELECT * FROM notify WHERE seeker='".$_SESSION['email']. "'
AND donor='".$email."' ORDER_BY `date` LIMIT 1";