MySQL syntax error when joining tables based on user input - php

Question

I have five tables that produce the results I need, but with five different queries.
Tables are [temperature, partSize, volume, stiffness and weight]. Each table has a column "type" that holds identical values among all tables.
The following queries gives me the results I need...but in five different tables.
$result_temp = mysqli_query($conn, "SELECT * FROM temperature WHERE '%{$_POST['temperature']}%' LIKE '%{$_SESSION['temperature']}%'");
$result_size = mysqli_query($conn, "SELECT * FROM partSize WHERE '%{$_POST['partSize']}%' LIKE '%{$_SESSION['partSize']}%'");
$result_vol = mysqli_query($conn, "SELECT * FROM volume WHERE '%{$_POST['volume']}%' LIKE '%{$_SESSION['volume']}%'");
$result_stiff = mysqli_query($conn, "SELECT * FROM stiffness WHERE '%{$_POST['stiffness']}%' LIKE '%{$_SESSION['stiffness']}%'");
$result_wght = mysqli_query($conn, "SELECT * FROM weight WHERE '%{$_POST['weight']}%' LIKE '%{$_SESSION['weight']}%'");
I need a solution that combines the results of these tables and I am stuck. I keep getting this error: mysqli_fetch_assoc() expects parameter 1 to be mysqli_result, boolean
I'm know mySQL will do this and I'm pretty sure it's a simple syntax error but I cannot figure this out.
I've tried this (and many variations...with CONCAT, without CONCAT, tick marks, no tick marks):
$result = mysqli_query($conn, "SELECT * FROM `temperature` WHERE CONCAT ('%{$_POST['partSize']}%') LIKE CONCAT ('%{$_SESSION['partSize']}%') INNER JOIN `partSize` ON temperature.type = partSize.type INNER JOIN `volume` ON partSize.type = volume.type INNER JOIN `stiffness` ON volume.type = stiffness.type INNER JOIN `weight` ON stiffness.type = weight.type ");
The problem seems to arise as soon as I try to INNER JOIN or JOIN the tables. I've spent hours on this already. :/ Can anyone help?

Answer 1

I don't know what version of PHP you're using, but I'd encourage you to switch to PDO and to also use prepared statements (regardless of your version). However the syntax for your statement should be:
SELECT [columns] FROM [first table] INNER JOIN [other tables] ON [first table] WHERE [conditions]
With that being said, take a look at this example:
<?php
$config = array(
'host' => '[db host ip]',
'username' => '[db username]',
'password' => '[db password]',
'name' => '[db name]'
);
$dsn = "mysql:dbname=$config[name];host=$config[host];charset=utf8mb4";
$db = new PDO($dsn, $config['username'], $config['password']);
$db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$db->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);
$stmt = $db->prepare('
SELECT
*
FROM
`temperature` AS t
INNER JOIN `partSize` AS p ON t.`type` = p.`type`
INNER JOIN `volumne` AS v ON t.`type` = v.`type`
INNER JOIN `stiffness` AS s ON t.`type` = s.`type`
INNER JOIN `weight` AS w ON t.`type` = w.`type`
WHERE
t.`temperature` LIKE CONCAT('%', :temperature, '%') AND
t.`partSize` LIKE CONCAT('%', :partSize, '%') AND
t.`volumne` LIKE CONCAT('%', :volumne, '%') AND
t.`stiffness` LIKE CONCAT('%', :stiffness, '%') AND
t.`weight` LIKE CONCAT('%', :weight, '%');');
// Execute the query passing the $_POST values as the parameters
$stmt->execute(array(
':temperature' => $_POST['temperature'],
':partSize' => $_POST['partSize'],
':volume' => $_POST['volume'],
':stiffness' => $_POST['stiffness'],
':weight' => $_POST['weight']
);
// Get all of the rows returned by the query and store them in an associative array
$rows = $stmt->fetchAll(PDO::FETCH_ASSOC);
?>