从一个表中获取ID并将其插入另一个表中

Question

So basically, the users gonna input the students ID, first name, last name, teacher's first name and teacher's last name. I want to get the ID which is corresponding to the teacher's first and last name.

Here's My Code:

$get_teacher = mysqli_query($link, "SELECT id FROM teachers WHERE first_name = '$teacher_first_name' AND last_name = '$teacher_last_name'");

$get_teacher_arr = mysqli_fetch_array($get_teacher);

$result = mysqli_query($link, "INSERT INTO students (student_id, first_name, last_name, teacher_id) VALUES ('$student_id', '$first_name', '$last_name', '$get_teacher_arr[0]');");

Answer 1

Do it in one query

INSERT INTO students (student_id, first_name, last_name, teacher_id) 
SELECT $student_id, '$first_name', '$last_name', id 
FROM teachers 
WHERE first_name = '$teacher_first_name' 
AND last_name = '$teacher_last_name'