Simple NoSQL entirely in PHP

example.php

<?php
$time1 = microtime(true);
include "lib.php";
try{
    $db = new array_db("db1");
}catch(Exception $e){
    echo $e->getMessage();
}
$db->install([
    "users" => [
        ["id","username","password"],
        [0,"AliReza",md5("")]
    ]
]);
$search = $db->select("users",["==" => ["username" => $_GET['u'],"password" => md5($_GET['p'])]]);
if($search->rowCount === 1){
    echo "Hi ".$_GET['u'];
}else{
    echo "Hi guest";
}
$time2 = microtime(true);
echo '<br><b>Total Execution Time:</b> '.($time2-$time1).' Memory usage:'.memory_get_usage();
echo "<br>Users count:".$db->selectAll("users")->rowCount;

lib.php

<?php

/**
 * Class array_db
 */
class array_db {
    /**
     * @var array|null
     */
    protected  $db = null;

    /**
     * @var string|null
     */
    protected $file_name = null;

    /**
     * @var bool
     */
    protected $first_run = false;

    /**
     * @param $db
     * @throws Exception
     */
    public function __construct($db){
        if(is_string($db)){
            $this->file_name = $db;
            if(!file_exists($db.".php")){
                $this->save();
                $this->first_run = true;
            }else{
                $this->load();
            }
        }else{
            throw new Exception("Error:database isn't string");
        }
    }

    public function install($database){
        if($this->first_run === true){
            $this->db = $database;
            $this->save();
        }
    }

    /**
     * @param string $table
     * @param int|array $where
     * @param int $limit : show all rows if its 0
     * @return stdClass
     * @throws Exception
     */
    public function select($table,$where = 1,$limit = 0){
        /**
         * @param $where = [
         *  "==,!=,LIKE" => ['column' => value,...]
         * ]
         */
        if(isset($this->db[$table])){
            $p = $this->db[$table];
        }else{
            throw new Exception("Error:can't found `".$table."` in database");
        }
        $re = [];
        if($where === 1){
            if($limit === 0){
                $count = count($p)-1;
                for($i = 1;$i <= $count;$i++){
                    $_count = count($p[$i])-1;
                    for($b = 0;$b <= $_count;$b++){
                        $re[$i][$p[0][$b]] = $p[$i][$b];
                    }
                }
            }else{
                $count = count($p)-1;
                if($limit > $count){
                    $limit = $count;
                }
                for($i = 1;$i <= $limit;$i++){
                    $_count = count($p[$i])-1;
                    for($b = 0;$b <= $_count;$b++){
                        $re[$i][$p[0][$b]] = $p[$i][$b];
                    }
                }
            }
        }else{
            if($limit === 0){
                $count = count($p)-1;
                $bl    = [];
                for($i = 1;$i <= $count;$i++){
                    $_count = count($p[$i])-1;
                    for($b = 0;$b <= $_count;$b++){
                        if(isset($where["=="])){
                            if(isset($where["=="][$p[0][$b]])){
                                if($where["=="][$p[0][$b]] == $p[$i][$b]){
                                    $re[$i][$p[0][$b]] = $p[$i][$b];
                                }else{
                                    $bl[] = $i;
                                    unset($re[$i]);
                                }
                            }
                        }
                        if(isset($where["!="])){
                            if(isset($where["!="][$p[0][$b]])){
                                if($where["!="][$p[0][$b]] != $p[$i][$b]){
                                    $re[$i][$p[0][$b]] = $p[$i][$b];
                                }else{
                                    $bl[] = $i;
                                    unset($re[$i]);
                                }
                            }
                        }
                        if(isset($where[">"])){
                            if(isset($where[">"][$p[0][$b]])){
                                if($where[">"][$p[0][$b]] > $p[$i][$b]){
                                    $re[$i][$p[0][$b]] = $p[$i][$b];
                                }else{
                                    $bl[] = $i;
                                    unset($re[$i]);
                                }
                            }
                        }if(isset($where[">="])){
                            if(isset($where[">="][$p[0][$b]])){
                                if($where[">="][$p[0][$b]] >= $p[$i][$b]){
                                    $re[$i][$p[0][$b]] = $p[$i][$b];
                                }else{
                                    $bl[] = $i;
                                    unset($re[$i]);
                                }
                            }
                        }
                        if(isset($where["<"])){
                            if(isset($where["<"][$p[0][$b]])){
                                if($where["<"][$p[0][$b]] < $p[$i][$b]){
                                    $re[$i][$p[0][$b]] = $p[$i][$b];
                                }else{
                                    $bl[] = $i;
                                    unset($re[$i]);
                                }
                            }
                        }if(isset($where["<="])){
                            if(isset($where["<="][$p[0][$b]])){
                                if($where["<="][$p[0][$b]] <= $p[$i][$b]){
                                    $re[$i][$p[0][$b]] = $p[$i][$b];
                                }else{
                                    $bl[] = $i;
                                    unset($re[$i]);
                                }
                            }
                        }
                        if(!in_array($i,$bl)){
                            $re[$i][$p[0][$b]] = $p[$i][$b];
                        }
                    }
                }
            }else{
                $count = count($p)-1;
                if($limit > $count){
                    $limit = $count;
                }
                $bl    = [];
                for($i = 1;$i <= $limit;$i++){
                    $_count = count($p[$i])-1;
                    for($b = 0;$b <= $_count;$b++){
                        if(isset($where["=="])){
                            if(isset($where["=="][$p[0][$b]])){
                                if($where["=="][$p[0][$b]] == $p[$i][$b]){
                                    $re[$i][$p[0][$b]] = $p[$i][$b];
                                }else{
                                    $bl[] = $i;
                                    unset($re[$i]);
                                }
                            }
                        }
                        if(isset($where["!="])){
                            if(isset($where["!="][$p[0][$b]])){
                                if($where["!="][$p[0][$b]] != $p[$i][$b]){
                                    $re[$i][$p[0][$b]] = $p[$i][$b];
                                }else{
                                    $bl[] = $i;
                                    unset($re[$i]);
                                }
                            }
                        }
                        if(!in_array($i,$bl)){
                            $re[$i][$p[0][$b]] = $p[$i][$b];
                        }
                    }
                }
            }
        }
        $return = new stdClass();
        $return->fetchArray = $re;
        $return->rowCount   = count($re);
        return $return;
    }

    /**
     * @param string $table
     * @return array
     * @throws Exception
     */
    public function selectColumn($table){
        if(isset($this->db[$table])){
            $re     = $this->db[$table][0];
            $return = new stdClass();
            $return->fetchArray = $re;
            $return->rowCount   = count($re);
            return $return;
        }else{
            throw new Exception("Error:can't found `".$table."` in database");
        }
    }

    /**
     * @param string|int $table
     * @return stdClass
     * @throws Exception
     */
    public function selectAll($table = 0){
        if($table === 0){
            $re     = $this->db;
            $return = new stdClass();
            $return->fetchArray = $re;
            $return->rowCount   = count($re);
            return $return;
        }
        if(isset($this->db[$table])){
            $return     = $this->select($table);
            return $return;
        }else{
            throw new Exception("Error:can't found `".$table."` in database");
        }
    }

    /**
     * @return stdClass
     */
    public function selectTable(){
        $re     = array_keys($this->db);
        $return = new stdClass();
        $return->fetchArray = $re;
        $return->rowCount   = count($re);
        return $return;
    }



    /**
     * @param string $table
     * @param array $value
     * @throws Exception
     */
    public function insert($table,$value){
        if(isset($this->db[$table])){
            if(is_array($value)){
                $this->db[$table][] = $value;
            }else{
                throw new Exception("Error:value isn't array");
            }
        }else{
            throw new Exception("Error:can't found `".$table."` in database");
        }
    }

    /**
     * @param string $table
     * @param string $name
     * @throws Exception
     */
    public function newColumn($table,$name){
        if(isset($this->db[$table])){
            $this->db[$table][0] += [count($this->db[$table][0]) => $name];
        }else{
            throw new Exception("Error:can't found `".$table."` in database");
        }
    }

    /**
     * @param string $table
     * @param array $columns
     * @throws Exception
     */
    public function newTable($table,$columns){
        if(!isset($this->db[$table])){
            $this->db[$table] = $columns;
        }else{
            throw new Exception("Error:`".$table."` using now in database");
        }
    }

    /**
     * @param string $table
     * @param int|array $where
     * @throws Exception
     */
    public function drop($table,$where = 1){
        if(isset($this->db[$table])){
            if($where == 1){
                $this->db[$table] = [$this->db[$table][0]];
            }else{
                $where_o= $where;
                $where_n=[];
                if(isset($where_o['=='])){
                    $where_n['!='] = $where_o['=='];
                }
                if(isset($where_o['!='])){
                    $where_n['=='] = $where_o['!='];
                }
                if(isset($where_o['>'])){
                    $where_n['<'] = $where_o['>'];
                }
                if(isset($where_o['<'])){
                    $where_n['>'] = $where_o['<'];
                }
                if(isset($where_o['>='])){
                    $where_n['<='] = $where_o['>='];
                }
                if(isset($where_o['<='])){
                    $where_n['>='] = $where_o['<='];
                }
                $search = $this->select($table,$where_n)->fetchArray;
                $this->db[$table] = [$this->db[$table][0]];
                foreach($search as $row){
                    $this->db[$table][] = array_values($row);
                }
            }
        }else{
            throw new Exception("Error:can't found `".$table."` in database");
        }
    }

    /**
     * @param string $table
     * @throws Exception
     */
    public function dropTable($table){
        if(isset($this->db[$table])){
            unset($this->db[$table]);
        }else{
            throw new Exception("Error:can't found `".$table."` in database");
        }
    }

    /**
     * @param int|string $table
     * @return string
     * @throws Exception
     */
    public function toJSON($table = 0){
        if($table === 0){
            return json_encode($this->db);
        }else{
            if(isset($this->db[$table])){
                return json_encode($this->db[$table]);
            }else{
                throw new Exception("Error:can't found `".$table."` in database");
            }
        }
    }

    /**
     * @throws Exception
     */
    public function save(){
        $file_name  = 0;
        $table      = 0;
        if($file_name === 0){
            $file_name = $this->file_name;
        }
        $json = $this->toJSON($table);
        $re   = "<?php return json_decode('".str_replace("'",'\\\'',$json)."',true); ?>";
        file_put_contents($file_name.".php",$re);
    }

    /**
     * @throws Exception
     */
    public function load(){
        $file_name  = 0;
        $table      = 0;
        if($file_name === 0){
            $file_name = $this->file_name;
        }
        if($table === 0){
            if(file_exists($file_name.".php")){
                $this->db = include($file_name.".php");
            }else{
                throw new Exception("Error:file `".$file_name.".php` doesn't exists");
            }
        }else{
            $this->db[$table] = include($file_name.".php");
        }
    }
}