comparing php variable in sql query - php

Question

I am trying to compare php variable in the sql query as follows:
I have used '$a' as the way to compare. Any solution will provided will be quite helpful.
<?php
$username=$_SESSION['alogin'];
$sql = "SELECT kDepartment FROM USERS WHERE kUsername=:username ";
$query= $dbh -> prepare($sql);
$query-> bindParam(':username', $username, PDO::PARAM_STR);
$query->execute();
$results=$query->fetchAll(PDO::FETCH_OBJ);
if($query->rowCount() > 0)
{
foreach($results as $result2)
$a=$result2;
{?>
<?php }}?>
<?php
$sql2 = "SELECT BudgetInput.kBudgetAvailable FROM BudgetInput WHERE BudgetInput.kDepartment='$a' ";
$query2 = $dbh -> prepare($sql2);
$query2->execute();
$results2=$query2->fetchAll(PDO::FETCH_COLUMN, 0);
print htmlentities($a);
?>
I am unable to fetch the result.
When I remove WHERE BudgetInput.kDepartment='$a'; the UI works correctly.

Answer 1

The main issue that I can see with your code is that you are assigning an object ($result2 is the last entry in the array of objects returned by your query) to $a and then trying to use that as a string (I'm not sure why you're using PDO::FETCH_OBJ for your fetchAll call when you are only retrieving a single value but that's another question). Anyway, the fetchAll will return an anonymous object (see the manual) with one property, kDepartment. To use that value, change:
$sql2 = "SELECT BudgetInput.kBudgetAvailable FROM BudgetInput WHERE BudgetInput.kDepartment='$a' ";
to
$sql2 = "SELECT BudgetInput.kBudgetAvailable FROM BudgetInput WHERE BudgetInput.kDepartment='{$a->kDepartment}' ";
The other (minor) issue that I see is that you are using rowCount. This is not guaranteed to work for SELECT statements (see the manual) and since you have already done a fetchAll you don't need it, you can simply change
if($query->rowCount() > 0)
to
if (count($results) > 0)

Answer 2

All you need is a simple join - then you need one query instead of two. A query from the result of another query is rarely the best approach.
Here we prepare a query which selects the available budget from the BudgetInput table, where it has a matching kDpeartment in the USERS table, and a username matching the variable in $username.
<?php
session_start();
$username = $_SESSION['alogin'];
$stmt = $dbh->prepare("SELECT bi.kBudgetAvailable
FROM BudgetInput bi
JOIN USERS u ON u.kDepartment=bi.kDepartment
WHERE u.kUsername=?");
$stmt->execute([$username]);
if ($result = $stmt->fetch()) {
echo $result['kBudgetAvailable'];
} else {
echo "No results found";
}