Why can't insert my subject of gmail header info into a sqlite3 database?

Question

The code have been tested that all the message_id,uid,subject gmail header info can be inserted into my sqlite3 database.

<?php
    $db='/home/email.db';

   // function get_gmail  can get all the message_id,uid,subject gmail header info.
   function get_gmail(){
        $email_data=array();
        $hostname = '{imap.gmail.com:993/imap/ssl}';
        $username = '[email protected]';
        $password = 'yyyy';
        $inbox = imap_open($hostname,$username,$password);
        $nums=imap_num_msg($inbox);
        for ($i=1;$i<=$nums;$i++){
            $overview = imap_fetch_overview($inbox, $i, 0);
            $x1 = $overview[0]->message_id;
            $x2 = $overview[0]->uid;
            $x3 = $overview[0]->subject;
            $email_data[]=array($x1,$x2,$x3);
            }
        imap_close($inbox);
        return  $email_data;
        }

    //function insert_data can insert all the data into my sqlite3 database.
    function insert_data($array){
        Global $db;
        $dbh=new PDO("sqlite:{$db}");
        $dbh->beginTransaction();
        $sql = "INSERT INTO gmail(message_id,uid,subject) VALUES (?,?,?)";
        $query = $dbh->prepare($sql);
        foreach($array as $item){
            $query->execute($item);
            }
        $dbh->commit();
        $dbh->beginTransaction();
        $dbh=null;
    }

    $data=get_gmail();
    insert_data($data);
?>

A problem remains ,for example a email's subject is '=?GB2312?B?zbO8xtGnu/m0ocq10bXP7sS/?=' ,it was inserted into sqlite3 as the form '=?GB2312?B?zbO8xtGnu/m0ocq10bXP7sS/?=' ,i changed it into chinese characters in the form of utf-8 with the following code.

<?php
    $db='/home/email.db';

    function get_gmail(){
        mb_internal_encoding('UTF-8'); 
        $email_data=array();
        $hostname = '{imap.gmail.com:993/imap/ssl}';
        $username = '[email protected]';
        $password = 'yyyy';
        $inbox = imap_open($hostname,$username,$password);
        $nums=imap_num_msg($inbox);
        for ($i=1;$i<=$nums;$i++){
            $overview = imap_fetch_overview($inbox, $i, 0);
            $x1 = $overview[0]->message_id;
            $x2 = $overview[0]->uid;
            $x3 = $overview[0]->subject;
            $x3 = mb_decode_mimeheader($x3);
            $email_data[]=array($x1,$x2,$x3);
            }
        imap_close($inbox);
        return  $email_data;
        }


    function insert_data($array){
        Global $db;
        $dbh=new PDO("sqlite:{$db}");
        $dbh->beginTransaction();
        $sql = "INSERT INTO gmail(message_id,uid,subject) VALUES (?,?,?)";
        $query = $dbh->prepare($sql);
        foreach($array as $item){
            $query->execute($item);
            }
        $dbh->commit();
        $dbh->beginTransaction();
        $dbh=null;
    }

    $re=get_gmail();
    insert_data($re);
?>

There are two problems to be solved.

1.mb_decode_mimeheader
Not all the subject in MIME RFC 2047 format need to be changed , strings begins with =?GB2312 will be changed.
How to add a if-else structure to do the job?

2.The insert_data function can't be run .
PHP Fatal error: Call to a member function execute() on a non-object in on line 49
Some bug in $query->execute($item); ,Why the statement can be run when not to change the string with mb_decode_mimeheader function?

Answer 1

although I won't answer exactly "why" (sorry too late at night here) you can try using imap_mime_header_decode to make it possible to have it stored in the db. Make sure you treat it with iconv later as it s usually stored not in utf8. (in my case at least)

$x3 = $overview[0]->subject;
$subject =  imap_mime_header_decode(x3);
$subject = iconv('ISO-8859-2','utf-8',$subject[0]->text);