using mysql variable in where clause with PDO - php

Question

I'm still struggling to find out the best possible solution for binding one date as variable in SQL with PDO. So far I programmed a function in PHP which approximates times in a specific date. I only have one date but the dirtiest solution which I found would be to bind it twice which I wouldn't risk to keep my code clean. So I was thinking to set a variable which will be used then in Where Clause. That's my code so far:
<?php
function approximateAppo($date){
$link = OpenDB();
try {
$query = "SET #v1 = :date;
SELECT from, till
FROM termin
WHERE from >= CONVERT('#v1 08:00:00', DATETIME)
AND till <= CONVERT('#v1 20:00:00', DATETIME)
AND comp_id=:comp";
$statement = $link->prepare($query);
$statement->bindValue(':comp', $_SESSION['comp'],PDO::PARAM_INT);
$statement->bindValue(':date', $date, PDO::PARAM_STR);
$statement->execute();
$row = $statement->fetchAll();
} catch (PDOException $e){
p($e);
}
CloseDB($link);
return $row;
}
But it doesn't really work, what might be the issue in there? Or what is the best possible solution for solving the issue? I still haven't found anything similar for solving my case.

Answer 1

You can't execute multiple queries in a single call.
You can initialize a variable in a subquery.
Also, variables aren't replaced inside strings, you need to use CONCAT().
$query = "SELECT from, till
FROM termin
CROSS JOIN (SELECT #v1 := :date) AS x
WHERE from >= CONVERT(CONCAT(#v1, ' 08:00:00'), DATETIME)
AND till <= CONVERT(CONCAT(#v1, ' 20:00:00'), DATETIME)
AND comp_id=:comp";
But there isn't really a need for the variable, you can use the :date placeholder twice.
$query = "SELECT from, till
FROM termin
WHERE from >= CONVERT(CONCAT(:date, ' 08:00:00'), DATETIME)
AND till <= CONVERT(CONCAT(:date, ' 20:00:00'), DATETIME)
AND comp_id=:comp";