comparing sql date to php date

Question

I'm trying to write a sql query. In English, this query translates to...

select all records in database whose date_purchased field is less than [a date].

Here's the query in code form:

 // php formatting $date = date("Ymd"); // sql query SELECT food FROM fridge WHERE date_purchased <= "$date"

The problem I'm having is comparing the sql date ( the value of date_purchased) to a php date ( the $date variable I'm using in my query ). I know it's possible to include php variables in sql queries, but it seems like the php date and the sql date aren't of the same "type," so sql can't make the comparison.

I should mention as well that I've made sure that the php date in my query has the same formatting as the dates in the sql database. Both are in the form: YYYY-mm-dd . Nonetheless, this still seems to me like a type issue. Any insight is much appreciated.

Answer 1

I had a similar problem and these are the steps I took to resolve:

1. Change the SQL field type to datetime.
2. In php use $date = date('Ymd H:i:s ); to get the current date and time
3. update your query as SELECT food FROM fridge WHERE date_purchased <= '$date' (change your double qoutes to single qoute).

Answer 2

Try this:

SELECT * FROM tbl1 WHERE user_id = "User1" and date_purchased < "2016-01-01";

If you have a php datetime variable, use format to create a string:

$date->format('Y-m-d');

In a context this could look like this:

$date_str = $date->format('Y-m-d');
$sql_pattern = 'SELECT * FROM tbl1 WHERE user_id = "%s" and date_purchased < "%s";';
$sql = sprintf($sql_pattern, $user_name, $date_str);

Answer 3

Everything seems to be fine having in mind only the information you gave.

We would have to see the entire code to find the error. Maybe it's a MySQL field type problem, or maybe it's about the way you are sending the query to MySQL.

I have a working example here with a minimal version of your table. I hope it helps!

Fridge table fields:

mysql> desc fridge;
+----------------+------------------+------+-----+---------+----------------+
| Field          | Type             | Null | Key | Default | Extra          |
+----------------+------------------+------+-----+---------+----------------+
| id             | int(11) unsigned | NO   | PRI | NULL    | auto_increment |
| food           | varchar(20)      | YES  |     | NULL    |                |
| date_purchased | date             | YES  |     | NULL    |                |
+----------------+------------------+------+-----+---------+----------------+

(Note the date type in the date_purchased field).

Edit: this example works if you use either date or datetime type for that field.

Fridge table content:

mysql> select * from fridge;
+----+-----------+----------------+
| id | food      | date_purchased |
+----+-----------+----------------+
|  1 | hamburger | 2016-04-28     |
|  2 | pizza     | 2016-04-12     |
|  3 | salad     | 2016-05-10     |  <-- future date
|  4 | fruit     | 2016-05-04     |  <-- future date
+----+-----------+----------------+

PHP code (using statements to query the database):

<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";

// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);

if ($conn->connect_error) {
    die("Connection failed: " . $conn->connect_error);
}

// prepare and bind
$stmt = $conn->prepare("select food from fridge where date_purchased < ?");
$stmt->bind_param("s", $date);

// set parameters and execute
$date = date("Y-m-d");  // NOTE: $date stores the current date
echo "<p>Food with date < $date</p>";
$stmt->execute();

// bind variables to prepared statement
$stmt->bind_result($food);

// fetch values (here you can do whatever you want with results)
while ($stmt->fetch()) {
    echo "<p>$food</p>";
}

$stmt->close();
$conn->close();

Results (we don't want healthy food right now...):

Food with date < 2016-05-01

hamburger

pizza

Answer 4

I had the same problem and what seemed to work for me is the above (PHP code):

$cur_dt = date('Y-m-d');

          $sql = "SELECT date, text FROM rantevou WHERE user_id = '$id' ";
          $result = mysqli_query($link, $sql);

          if (mysqli_num_rows($result) > 0) {

            while($row = mysqli_fetch_assoc($result)){
              $date = $row["date"];
              if ($date <= $cur_dt){
                
              }
              
            }
          }

I also tried using convert function in sql query with no result.