Check if certain column has a duplicate value [closed] - php

Question

Closed. This question needs to be more focused. It is not currently accepting answers.
Want to improve this question? Update the question so it focuses on one problem only by editing this post.
Closed 3 years ago.
Improve this question
Name Number
1 Benjoe 001
2 Benjoe 002
3 Benjoe 001
Given the data, how can I determine that I found duplicate data (Row 1 and 3) using foreach? I have playing with this code right now.
Update: 02/14/2020 - I came up with this algorithm. I've added a flag to determine If I found a duplicate.
$results = [
['name' => 'Benjoe', 'number' => '001'],
['name' => 'Benjoe', 'number' => '002'],
['name' => 'Benjoe', 'number' => '001'],
];
foreach($results as $log) {
if($name == $log->vlg_full_name && $number == $log->vlg_contact_number) {
$isDuplicateNameAndNo = 1;
} else {
$isDuplicateNameAndNo = 0;
break;
}
$name = $log->vlg_full_name;
$number = $log->vlg_contact_number;
}

Answer 1

You can achieve this by a nested loop iterating throug the each element and compating it to the current one.
Try something like that:
<?php
$results = [
['name' => 'Benjoe', 'number' => '001'],
['name' => 'Benjoe', 'number' => '002'],
['name' => 'Benjoe', 'number' => '001'],
];
function compare($log1, $log2, $index1, $index2)
{
return $log1['name'] == $log2['name']
&& $log1['number'] == $log2['number']
&& $index1 != $index2;
}
foreach($results as $index1 => $log1) {
foreach ($results as $index2 => $log2) {
if (compare($log1, $log2, $index1, $index2)) {
echo "Item {$index1} has a duplicate at index {$index2}!<br/>\n";
}
}
}
Here is a link to working example on 3v4l.org
The output for the above will be:
Item 0 has a duplicate at index 2!<br/>
Item 2 has a duplicate at index 0!<br/>
If you don't need to exactly know wich items are duplicate you can simply concatenate the values and put them into an array, and check if the value is already there:
<?php
$results = [
['name' => 'Benjoe', 'number' => '001'],
['name' => 'Benjoe', 'number' => '002'],
['name' => 'Benjoe', 'number' => '001'],
];
$temp = [];
foreach($results as $index => $log) {
$val = $log['name'] . '_' . $log['number'];
if (in_array($val, $temp)) {
echo "Duplicate found at index {$index}<br/>\n";
} else {
$temp[] = $val;
}
}
Output:
Duplicate found at index 2<br/>
Working example on 3v4l.org
If you get your $results from database, another approach would be grouping the query by the requried columns and adding the count(*) field to gind out how many records exists.