Trying to remove duplicate lines from array acc. to column contents - php

Question

Using PHP and making a SELECT query from DB I am getting an output I don't like.
I start like this:
$details = Db::getInstance()->executeS($sql);
And I get, after a
echo json_encode($details);
For debug purposes:
[{"email":"test#on.gr","lastname":"TEST","firstname":"TEST1","id_lang":"1","id_order":"1"}]
[{"email":"test#on.gr","lastname":"OTHER","firstname":"DIFFERENT","id_lang":"1","id_order":"2"}]
[{"email":"test#on.gr","lastname":"THIRD","firstname":"DIFFERENT","id_lang":"1","id_order":"3"}]
[{"email":"new#on.gr","lastname":"THIRD","firstname":"NEW","id_lang":"1","id_order":"4"}]
What I want is to transform array $details to check on each "line" if the email column has unique values on the whole output. If yes to delete the lines that contain the duplicate entries and leave only the first that contain it.
Desired output:
[{"email":"test#on.gr","lastname":"TEST","firstname":"TEST1","id_lang":"1","id_order":"1"}]
[{"email":"new#on.gr","lastname":"THIRD","firstname":"NEW","id_lang":"1","id_order":"4"}]
(As you see lines with id order 2 and 3 where removed as they have the same email with the first)
Any kind of help will be highly appreciated.

Answer 1

Edit: just wanted to add up here that my code isn't in PHP. You have to change it.
Do an ORDER BY email command in the select statement.
Pseudo Code:
Loop through results:
String email1 = "";
String email2 = "";
for (i=0;i<(Detailssize); i++){
email2 = details[email][i]; //Do whatever you need to do to access the value of the email key here.
if(email2 != email1){
KEEP IT
}
else{
THROW AWAY
}
email1 = email2;
}
Obviously this is not PHP. It has been a while since i coded php. Nonetheless logically this should still work. I'm sure theres a way to change your SELECT statement to only return one from each value but i'm not good enough at SQL for that. This isn't as good of a solution but hope it helps.

Answer 2

Keep a list of emails you've seen before; whenever you encounter an email that has been seen before, skip that row.
Like this:
$newSet = array();
$seenBefore = array();
foreach( $details as $row ) {
if( isset( $seenBefore[ $row['email'] ) ) {
continue; // jump to the next row
}
// this email address must be new; add it to things we've seen before then add this row to the newSet
$seenBefore[$row['email']] = true;
$newSet[] = $row;
}
Then output $newSet in whichever way you want.