Changing cell value based on another cell - php

Question

I am working on a simple php app where I store employees data.
Basically, I have in MySQL few tables, one of them is Employees where I have many columns like name, position, costcenter, manager, etc...
Via php I am able to change the records in the table (simple CRUD).
What I want to achieve is when I change Position based on this Cost Center to be changed.
I have a separate table (CostCenters.sql) with all positions and their cost centers with a structure like this:
CostCenter
Position
124
Engineer
199
Manager
In my edit.php I am taking the positions from this table like this:
echo "<select name='position' required>";
include "dbConn.php";
$records = mysqli_query($db,
"SELECT position
from employees
WHERE id = $id
UNION SELECT jobtitle from costcenters");
while($data = mysqli_fetch_array($records))
{
echo "<option value='".$data['position'] ."'>"
.$data['position'] .
"</option>";
}
echo "</select>";`
In the same file for cost centers I have:
echo "<select name='costcenter' required>";
//echo "<option disabled selected>-- Избери --</option>";
include "dbConn.php";
$records = mysqli_query($db,
"SELECT costcenter, POSITION
FROM employees
WHERE id = $id
UNION ALL SELECT constcenternr, jobtitle
FROM costcenters ");
while($data = mysqli_fetch_array($records))
{
echo "<option value='".$data['costcenter'] ."'>"
.$data['costcenter'] . "-" .$data['POSITION'] . "
</option>";
}
echo "</select>";`
And my update query is very simple:
UPDATE employees
SET costcenter ='$costcenter',idcard ='$idcard',
personalnr ='$personalnr',position ='$position';
The question is how to make it when I update the record for Position to automatically changed also the CostCenter based on the value corresponding from (CostCenters.sql).
I have tried editing the select query for edit.php to union also the records from (CostCenters.sql) but had no success.
Here is my select query: (simple)
$result = mysqli_query($mysqli,
"SELECT * FROM employees WHERE id ='$id' ");
while($data = mysqli_fetch_array($result))
My first trial was to modify update query in this way:
UPDATE employees
SET costcenter =
(select costcenternr
from CostCenters
where ****),idcard ='$idcard',
personalnr = '$personalnr',position = '$position';
Frankly speaking, my SQL skills are not enough to complete this query