MySQL Querying Duplicates - php

Question

So, I have a database called teams, and it currently looks like this:
team_id | leader_id | student_id
1 | 123456 | 1234
2 | 1234 | 123456, 1234567890
3 | 1234 | 123456
4 | 0 | 12345, 1234, 1234567890
5 | 0 |
6 | 0 |
My students database looks like this
student_id | first_name | last_name
123456 | qwer | qwer
0 | asd | zxc
1234567890 | mmm |nnn
The user inputs a leader_id, and the user can input up to 7 student_id. The problem is that if the user inputs 1 student_id, everything is normal, but when the user inputs more than 1 student_id, than it stores the data more than once.
Example:
If the user enters 1234 as the leader_id, and enters 123456 and 1234567890 as the student_id, than it should store the data in one row, not separate the data into 2 rows.
Another thing is that in the last 3 rows, the user inputs 3 student_id, and the data gets stored in 1 row, but it adds 2 extra rows with nothing for the student_id
My PHP
<?php
error_reporting(0);
require '../../connect.php';
$leader_id = $_POST['leader_id'];
$student_id = array(
$_POST['student_id_1'],
$_POST['student_id_2'],
$_POST['student_id_3'],
$_POST['student_id_4'],
$_POST['student_id_5'],
$_POST['student_id_6']
);
$students_save = array();
if(!empty($leader_id)) {
foreach ($student_id as $id) {
if(!empty($id)) {
array_push($students_save, $id);
}
}
foreach ($students_save as $save) {
$check_id = mysqli_query($link, "SELECT student_id FROM students WHERE student_id = $save");
if(mysqli_num_rows($check_id)>0) {
$students_save = implode(", ", $students_save);
$result = mysqli_query($link, "INSERT INTO teams (leader_id, student_id)
VALUES ('$leader_id', '$students_save');");
if($result) {
header("Location: ../../../admin.php?message=Success!");
} else {
header("Location: ../../../admin.php?message=Sorry we ran into an error");
}
} else {
header("Location: ../../../admin.php?message=A Student ID Doesn't Exist");
}
}
} else if(empty($leader_id)){
header("Location: ../../../admin.php?Please add you're input values");
}
?>

Answer 1

As you edited your question,
all you need is to break out of your foreach loop, if you $result is
successfull so add break in if($result) rest of the code will remain
the same
See the code below
<?php
foreach ($students_save as $save) {
$check_id = mysqli_query($link, "SELECT student_id FROM students WHERE student_id = $save");
if(mysqli_num_rows($check_id)>0) {
$students_save = implode(", ", $students_save);
$result = mysqli_query($link, "INSERT INTO teams (leader_id, student_id)
VALUES ('$leader_id', '$students_save');");
if($result) {
header("Location: ../../../admin.php?message=Success!");
break; // add break here, as if your condition
} else {
header("Location: ../../../admin.php?message=Sorry we ran into an error");
}
} else {
header("Location: ../../../admin.php?message=A Student ID Doesn't Exist");
}
}

Answer 2

Try the below code if it helps,
<?php
error_reporting(0);
require '../../connect.php';
$leader_id = $_POST['leader_id'];
$student_id = array();
if(isset($_POST['student_id_1'])) $student_id[] = $_POST['student_id_1'];
if(isset($_POST['student_id_2'])) $student_id[] = $_POST['student_id_2'];
if(isset($_POST['student_id_3'])) $student_id[] = $_POST['student_id_3'];
if(isset($_POST['student_id_4'])) $student_id[] = $_POST['student_id_4'];
if(isset($_POST['student_id_5'])) $student_id[] = $_POST['student_id_5'];
if(isset($_POST['student_id_6'])) $student_id[] = $_POST['student_id_6'];
if(!empty($leader_id)) {
$students_save = implode(", ", $student_id);
$check_id = mysqli_query($link, "SELECT student_id FROM students WHERE student_id IN ($students_save)");
if(mysqli_num_rows($check_id)>0) {
//$student_ids = array();
//while($row = $check_id->fetch_array(MYSQLI_ASSOC)) $student_ids[] = $row['student_id'];
//$students_save = implode(", ", $student_ids);
$result = mysqli_query($link, "INSERT INTO teams (leader_id, student_id) VALUES ('$leader_id', '$students_save');");
if($result) {
header("Location: ../../../admin.php?message=Success!");
} else {
header("Location: ../../../admin.php?message=Sorry we ran into an error");
}
} else {
header("Location: ../../../admin.php?message=A Student ID Doesn't Exist");
}
} else if(empty($leader_id)) {
header("Location: ../../../admin.php?Please add you're input values");
}
?>
This code should help you.
Note: I have added comment to a part of the code. If you remove the commenting, then it will only insert the student_id which exists in the students table.