Get data from database using php,ajax

in you dataAll.php

If you have select All available industries
you shold not check for sector because you need all sector (eventually you should check for countries ) so you should avoid the check for this condition

<?php

$conn = mysqli_connect("localhost", "root", "", "love");
$result = mysqli_query($conn, "SELECT * FROM meed");
$data = [];

$wynik = [];
$totalProjects = 0;
$totalBudget = 0;

while ($row = mysqli_fetch_array($result)) {
    $totalProjects += $row['SumofNoOfProjects'];
    $totalBudget += $row['SumofTotalBudgetValue'];
}
echo json_encode([$totalProjects, $totalBudget]);

You can use the SQL JOIN operator, or in this case an implicit join would be cleanest:

$result = mysqli_query($conn, "SELECT * FROM construction, power, oil_and_gas, industrial WHERE construction.Countries = power.Countries AND power.Countries = oil_and_gas.Countries AND oil_and_gas.Countries = industrial.Countries");

You need the WHERE conditions so it knows how the rows of each different table are related to each other. You can shorten it a bit with aliases for the tables:

$result = mysqli_query($conn, "SELECT * FROM construction as C, power as P, oil_and_gas as G, industrial as I WHERE C.Countries = P.Countries AND P.Countries = G.Countries AND G.Countries = I.Countries");

In this case, however, I think you may want to consider changing the structure of your database. It seems like you repeat columns quite a bit across them. Perhaps these can all be in a single table, with a "type" column that specifies whether it's power, construction, etc. Then you can query just the one table and group by country name to get all your results without the messy joins across 4 tables.