List 1 row and not all rows in php - php

Question

For some reason this is returning everything from the member_details table when all i want is to return a single row that equals to the selected item in the drop down list.
Here is the php for it: i thought it would return the row which equaled the value of the drop down but its just listing it all.
<?php
if (isset($_POST['members'])) {
$ResultSet = getTableResults("member_details");
echo "<h1> Member Details </h1>";
echo "<table border='1' cellpadding='6'>";
echo "<tr> <th>Id</th> <th>Name</th> <th>Job</th> <th>Wage</th> <th>Hobby</th> ";
foreach ($ResultSet as $row) {
echo "<tr>";
echo "<td>" . $row ['member_id'] . "</td>";
echo "<td>" . $row['first_name'] . " " . $row ['second_name'] . "</td>";
echo "<td>" . $row['job'] . "</td>";
echo "<td>" . $row['wage'] . "</td>";
echo "<td>" . $row['hobby'] . "</td>";
echo "</tr>";
}
echo "<table>";
}
?>
If you want to see more code to make more sense of it please ask and il edit and update the question.
function getTableResults() {
$sql = "SELECT DISTINCT member_details.member_id, members.first_name, members.second_name, member_details.wage, member_details.job, member_details.hobby
FROM members
INNER JOIN member_details
ON members.member_id=member_details.member_id";
$mysqlConnection = getSQLConnection();
$ResultSet = $mysqlConnection->query($sql);
return $ResultSet;
}

Answer 1

You do not have any Condition while requesting your information, getTableResults() fetches all Data that is stored to your table. You need to change that function and add a WHERE xy condition. Probably something like this:
function getTableResults( $id ) {
$sql = "SELECT DISTINCT member_details.member_id, members.first_name,members.second_name, member_details.wage, member_details.job, member_details.hobby
FROM members
INNER JOIN member_details
ON members.member_id=member_details.member_id WHERE member_details.member_id = '$id'";
$mysqlConnection = getSQLConnection();
$ResultSet = $mysqlConnection->query($sql);
return $ResultSet;
}
Then Call the function with the requred member-id as parameter.
Anyway, I'd recommend you to inform yourself about prepared statements to prevent SQL-Injection here!