Pass Value inside row array to another variable name? - php

Question

How to pass value inside row array to another variable since the result of the row array I need to do another query for selection in other table. In both echo $row['Plate'] and $plateID can show the value, but for another query doesn't show the result. This is my code:
<?php
$connection=mysqli_connect("localhost","root","");
$db=mysqli_select_db($connection,'db_car_identification');
$q="SELECT Plate FROM addplate ORDER BY ID DESC LIMIT 1 ";
$result=mysqli_query($connection,$q);
while($row = mysqli_fetch_array($result)) {
echo $row['Plate'];
$plateID = $row['Plate'];
echo $plateID;
$query="SELECT StuName FROM student_detail WHERE plateID=$plateID";
$query_run=mysqli_query($connection,$query);
while($row1=mysqli_fetch_array($query_run)) {
echo $row1['StuName'];
}
}
?>

Answer 1

You should really be using parameterized prepared statements.
However, in your example you could simply use an SQL subquery instead. It would make your code much simpler.
mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
$connection = new mysqli("localhost", "root", "", 'db_car_identification');
$connection->set_charset('utf8mb4');
$result = $connection->query('SELECT StuName, Plate
FROM student_detail
WHERE plateID = (SELECT Plate FROM addplate ORDER BY ID DESC LIMIT 1)');
foreach($result as $row1){
echo $row1['StuName'];
}

Answer 2

Please check some step
For 1st Query Result which datatype is it?
If it is Integer or any numeric data type then echo the $query variable and check whatever query is right or wrong by simply copy and paste it into database query builder (phpmyadmin).
If it is String data type then simply add '' to your $plateID variable in query. eg:"SELECT StuName FROM student_detail WHERE plateID='$plateID'" (If not working then echo again and check your query problem)
Let me know if this help.