Building a RFID log-in system in MySQL - mysql

Question

I'm trying to build an automatic attendance site using RFID, currently MySQL already records the time and date a student enters the campus, but I want each attendance tagged as either "late" or "on-time" using the time they entered the campus.
For example Student A taps his RFID at the gate at 7:11 AM this would be tagged as LATE, Student B taps her RFID at the gate at 6:55AM and this would tagged as early in MySQL.
I am a beginner in JavaScript, MySQL and jQuery so I don't know which code to use. I'm self taught so I try to search for tutorials online, but for this one it seems that I cannot find tutorials for it.
Here's my code for the RFID tag.
<?php
require_once 'admin/connect.php';
$student = $_POST['student'];
$time = date("H:i", strtotime("+8 HOURS"));
$date = date("Y-m-d", strtotime("+8 HOURS"));
$q_student = $conn->query("SELECT * FROM `student` WHERE `student_no` = '$student'") or die(mysqli_error());
$f_student = $q_student->fetch_array();
$student_name = $f_student['firstname']." ".$f_student['lastname'];
$conn->query("INSERT INTO `time` VALUES('', '$student', '$student_name', '$time', '$date')") or die(mysqli_error());
echo "<h3 class = 'text-muted'>".$student_name." <label class = 'text-info'>at ".date("h:i a", strtotime($time))."</label></h3>";
This is what my database currently looks like when a students taps his/her ID:
https://imgur.com/a/dgwMJ5i
Hi! I'm Getting MYSQL Errors i dont know how to troubleshoot
.\libraries\classes\Display\Results.php#4196: PhpMyAdmin\Display\Results->_getSortedColumnMessage(
,
string 'student_name',
)
.\libraries\classes\Sql.php#1666: PhpMyAdmin\Display\Results->getTable(
,
array,
array,
boolean true,
)
.\libraries\classes\Sql.php#1468: PhpMyAdmin\Sql->getHtmlForSqlQueryResultsTable(
,
string './themes/pmahomme/img/',
NULL,
array,
boolean false,
integer 0,
integer 0,
boolean true,
,
array,
boolean true,
)
.\libraries\classes\Sql.php#2250: PhpMyAdmin\Sql->getQueryResponseForNoResultsReturned(
array,
string 'db_sars',
string 'time',
NULL,
integer 0,
,
NULL,
string './themes/pmahomme/img/',
NULL,
,
string 'SELECT date, student_no, student_name, time, CASE WHEN time > \'07:00\' THEN \'LATE\' ELSE \'ON TIME\' END AS tag FROM time WHERE date >= CURDATE() - INTERVAL 7 DAY AND time BETWEEN \'05:00\' AND \'09:00\' ORDER BY date, student_name',
NULL,
)
.\import.php#758: PhpMyAdmin\Sql->executeQueryAndGetQueryResponse(
array,
boolean false,
string 'db_sars',
string 'time',
NULL,
NULL,
NULL,
NULL,
NULL,
NULL,
string 'tbl_structure.php',
string './themes/pmahomme/img/',
NULL,
NULL,
NULL,
string 'SELECT date, student_no, student_name, time, CASE WHEN time > \'07:00\' THEN \'LATE\' ELSE \'ON TIME\' END AS tag FROM time WHERE date >= CURDATE() - INTERVAL 7 DAY AND time BETWEEN \'05:00\' AND \'09:00\' ORDER BY date, student_name',
NULL,
NULL,
)

Answer 1

(Please avoid using images to show key parts of your problem).
It looks like your time table contains these columns:
student
student_name
time
date
It looks like you have no information about whether a student is arriving or departing. That makes your logic a little trickier. Let's assume any row of your time table between 05:00 and 09:00 means an arrival, and that any arrival after 07:00 is considered late. You can get a list of student arrivals in the last week with this query. They'll have the tag LATE when needed or ON TIME otherwise.
SELECT `date`, student, student_name, `time`,
CASE WHEN time > '07:00' THEN 'LATE' ELSE 'ON TIME' END AS tag
FROM `time`
WHERE `date` >= CURDATE() - INTERVAL 7 DAY
AND `time` BETWEEN '05:00' AND '09:00'
ORDER BY `date`, `student`
I guess that's what you mean by tagging each attendance.
Edit If you want to show these tags LATE on your web site, you need no extra column in the database. Just use a query like the one I showed; the query itself contains the rule defining lateness and applies the tag. Then display the results from the query. It's generally not a good idea to alter a table to insert conditions you can derive from the existing content of each row. (That's different if you have hundreds of millions of rows and must denormalize your table to gain performance. But you're nowhere near that point.)
Pro tip Don't use reserved words like DATE and TIME for the names of tables or columns. Doing so makes it harder to track down bugs.