Disease-Symptom relation in MySQL - php

Question

I am making an electronic health system related to patient diagnosing in PHP and MySQL. I have made following tables in database with the following records:
Illness(illness_id(PK), illness_code,illness_name)
Symptom(symptom_id, illness_id(FK),symptom_name ).
Now, what I would like to do is that, I will write name of symptom in search bar and after clicking button, related diseases should be output. Could you tell me SQL query that will output appropriate diseases please?

Answer 1

Please try this. After you retrieve the symptom value from the search bar into a variable, say symptom_name_provided_in_search_bar, you can use that value in the below query
select illness_name
from illness a, symptom b
where a.illness_id = b.illness_id
and b.symptom_name = :symptom_name_provided_in_search_bar

Answer 2

For this to work you should create only one table illness with 2 rows:
illnessName and illnessSymptom. Note: This will only work if the symptom is written exactly as in the database.
<?php
$host = 'yourmysqlhost';
$user = 'yourmysqluser';
$pass = 'yourmysqlpassword';
$db = 'yourmysqldatabase';
$symptom = $_POST['symptom'];
$connect = mysqli_connect($host, $user, $pass, $db);
$sanitizedSymptom = mysqli_real_escape_string($connect, $symptom);
$query = mysqli_query($connect, "SELECT * FROM illness WHERE illnessSymptom = '".$sanitizedSymptom."'");
if(mysqli_num_rows($query) == 0)
{
echo '<p>No results...</p>';
}
else
{
while($row = mysqli_fetch_assoc($query))
{
echo '<h1>'.$row['illnessName'].'</h1>';
echo '<p>Symptom: '.$row['illnessSymptom'].'</p>';
echo '<br>';
}
}
?>
Edit:
To find a symptom that is approximately like the symptom in the database, the query should be like this:
$query = mysqli_query($connect, "SELECT * FROM illness WHERE illnessSymptom LIKE '%".$sanitizedSymptom."%'");