Set a PHP variable based on first option in a form? - php

Question

I have a form that has a list of school courses. I have a PHP variable that is passed to an SQL statement based on the value of whatever option is selected. My issue is that when the page first loads, the variable has no value. Ideally, I'd like to be able to set the variable to whatever the first option in the form is.
Form:
<form method="post">
<select name="courseID">
<option value = "204" selected>Course 1</option>
<option value = "205"> Course 2 </option>
<option value ="206"> Course 3 </option>
</select>
<input id="button" type="submit" value = "Go" />
</form>
PHP & SQL
//get posted value from form - returns false if no value is selected
$course_id = $_POST['courseID'];
//prepared statement
//test query "SELECT * FROM [database] WHERE course_id = ?";
$sql = "SELECT A.title as course_title, B.body, C.title
FROM db.course as A,
db.objective as B,
db.competency as C,
db.course_objective_competency as D
WHERE
A.course_id = ? AND
A.course_id = D.course_id AND
B.objective_id = D.objective_id AND
C.competency_id = D.competency_id";
//prepare the query
$q = $con->prepare($sql);
//bind parameter to query (index, variable, type)
$q->bindParam(1,$course_id,PDO::PARAM_INT);
//execute the statement
$q->execute();

Answer 1

You can always do it like this:
$course_id = $_POST['courseID'] ?: 204;

Answer 2

if php code is in a separate file you have to add it to the action attribute for the form. Otherwise the values will never be sent to it
<form method="post" action='yourPhpFile.php'>
<select name="courseID">
<option value = "204" selected>Course 1</option>
<option value = "205"> Course 2 </option>
<option value ="206"> Course 3 </option>
</select>
<input id="button" type="submit" value = "Go" />
</form>