php if duplicate entry code example

Example 1: get duplicate value from array php

$arr = array(1, 4, 6, 1, 8, 9, 4, 6);

$unique = array_unique($arr);

$duplicates = array_diff_assoc($arr, $unique);

print_r($duplicates);
Array ( [3] => 1 [6] => 4 [7] => 6 )

Example 2: code to set error for du[licate entry in php

mysqli_query('INSERT INTO ...');
if (mysqli_errno() == 1062) {
    print 'no way!';
}