mysql碰到特殊字符，造成了数据不全

header('Content-type: text/html;charset=utf-8');
$s = '6b6Z5Y2O8K+gpQ==';
echo $t = base64_decode($s), PHP_EOL;
echo bin2hex($t);

header('Content-type: text/html;charset=utf-8');
$s = '6b6Z5Y2O8K+gpTEyMzEyMzEyMw==';
$t = base64_decode($s). PHP_EOL;
echo $t.'
';
echo filter_utf8_char($t);

/** 過濾字符串,保留UTF8字母數字中文及部份符號 
*   @param  String  $ostr 
*   @return String 
*/  
function filter_utf8_char($ostr){  
    preg_match_all('/[\x{FF00}-\x{FFEF}
------解决思路----------------------
\x{0000}-\x{00ff}
------解决思路----------------------
\x{4e00}-\x{9fff}]+/u', $ostr, $matches);  
    $str = join('', $matches[0]);  
    if($str==''){   //含有特殊字符需要逐個處理  
        $returnstr = '';  
        $i = 0;  
        $str_length = strlen($ostr);  
        while ($i<=$str_length){  
            $temp_str = substr($ostr, $i, 1);  
            $ascnum = Ord($temp_str);  
            if ($ascnum>=224){  
                $returnstr = $returnstr.substr($ostr, $i, 3);  
                $i = $i + 3;  
            }elseif ($ascnum>=192){  
                $returnstr = $returnstr.substr($ostr, $i, 2);  
                $i = $i + 2;  
            }elseif ($ascnum>=65 && $ascnum<=90){  
                $returnstr = $returnstr.substr($ostr, $i, 1);  
                $i = $i + 1;  
            }elseif ($ascnum>=128 && $ascnum<=191){ // 特殊字符  
                $i = $i + 1;  
            }else{  
                $returnstr = $returnstr.substr($ostr, $i, 1);  
                $i = $i + 1;  
            }  
        }  
        $str = $returnstr;  
        preg_match_all('/[\x{FF00}-\x{FFEF}
------解决思路----------------------
\x{0000}-\x{00ff}
------解决思路----------------------
\x{4e00}-\x{9fff}]+/u', $str, $matches);  
        $str = join('', $matches[0]);  
    }  
    return $str;  
}