Get staff name from table STAFF - mysqli

Question

can anyone provide me with solution for my coding. For your information, I made a query from my answer table which only consist id, staff_id, dept_name, question_id, ans, evaluator, and year. Below is my code:-
// Make a mysqli Connection
$connect = new mysqli('localhost', 'root', '', 'cpsdatabase');
//Mean by staff Id
$dept_name = $_GET['dept_name'];
$query = "SELECT staff_id,dept_name, AVG(ans)
FROM hodanswer WHERE dept_name='$dept_name'
group by staff_id";
$result=mysqli_query($connect, $query);
// Print out result
while($row = mysqli_fetch_array($result))
{
echo "The mean of staff id = &nbsp". $row['staff_id']."&nbsp&nbsp from department &nbsp".$row['dept_name']." &nbsp &nbsp &nbsp is &nbsp &nbsp". $row['AVG(ans)'];
echo "<br />";
}
I want to find mean and I did get the result. My problem is I want to retrieve the staff name based on staff id but staff name does not include in answer table. Staff name provided in staff table. How can I retrieve staff_name from table STAFF and display result based on code above. Please help me.

Answer 1

If I'm understanding your tables correctly then this should work. This will perform an inner join between tables STAFF and hodanswer and will display all staff id and staff name from table STAFF, respectively, where the staff id is equal to the staff_id(s) that are present in table hodanswer.
SELECT a.id, a.staff_name FROM STAFF a INNER JOIN hodanswer b ON a.id = b.staff_id;
Google up SQL INNER JOIN