从sum将可选值插入db列

Question

I am building a database that looks like a student grade book With four subjects, total and grade. I created six tables in mysqli db with the following names Eng1. Eng2 eng3 engtotal enggrade.

I have prepared an insertion script for the first four tables, I have also written the sum code which will handle the engtotal column insertion.

Now I need to include the grading code which will insert (a,b,c or d) Assuming the student total score is 80 and above it will insert (a) into the enggrade column if 79 to 50 it will insert (b) etc. Below is the codes I have managed to write.

$sql="INSERT INTO test ( fullname,
password, regno,  sclass, fcomment, ftname, nclass, eng1, eng2, eng3, eng4,
engtotal) Values( '', '".$fullname."', 
'".$password."',
'".$regno."',
'".$sclass."',
'".$fcomment."',
'".$ftname."',
'".$nclass."',
'".$eng1."',
'".$eng2."',
'".$eng3."',
 '".$eng4."', ('".$eng1+$eng2+eng3+eng4."') AS SUM);";

$query_new_user_insert = $this->db_connection->query($sql);

Answer 1

I have solved my problem. I used select instead of insert my solution in below.

$sql = "SELECT total, field1, field2, field3, CASE WHEN total >=70 THEN 'A' WHEN total BETWEEN 69 AND 55 THEN 'B' ELSE 'C' END AS 'field4'