无意义

这里的东西都是没什么意义的，个人练习的一些东西。

<?php
namespace database;
function p($arr, $p=null) {
    echo '<pre>'."\n";
    if($p==null) {
        print_r($arr);
    }else{
        var_dump($arr);
    }
    echo '</pre>';
}
class Mysql_db {
    private static $instance = null;
    private static $hostname        = 'localhost';
    private static $username        = 'root';
    private static $password        = 'root';
    private static $database        = '';
    protected $columns       = [];// the columns of specific table
    private $client_info     = null;
    private $server_info     = null;
    private $server_version  = null;
    private $client_version  = null;
    private $last_insert_id  = null;
    private $mysqli          = null;

    // initialize data parameters
    public function __construct($hostname, $username, $password, $database) {
        self::$hostname       = $hostname;
        self::$username       = $username;
        self::$password       = $password;
        self::$database       = $database;
        // 连接数据库
        $this->mysqli         = $this->connect();

        $this->client_version = mysqli_get_client_version();
        $this->client_info    = mysqli_get_client_info();
        $this->server_version = $this->_get_server_version();
        $this->server_info    = $this->_get_server_info();
    }

    public function __get($name) {
        return $this->$name;
    }

    private function _error_msg($msg) {
        return "[".date("Y-m-d H:i:s")."] ".$msg."\n";
    }

    private function _get_server_version() {
        return $this->mysqli->server_version;
    }
    private function _get_server_info() {
        return $this->mysqli->server_info;
    }

    // database connection
    public function connect() {
        $mysqli = @new \mysqli(self::$hostname, self::$username, self::$password, self::$database);
        if($mysqli->connect_error) {
            $e_msg = $this->_error_msg('Database Connection Error, '.$mysqli->connect_errno.': '.$mysqli->connect_error);
            die($e_msg);
        }
        return $mysqli;
    }

    // create database
    public function create_database($dbname) {
        if( !$dbname ) {
            $e_msg = "Database name is required";
            die($e_msg);
        }
        $sql = "create database ".'`'.$dbname.'`';

        if($this->mysqli->query($sql)) {
            $s_msg = 'Database created successfully';
            return $s_msg;
        } else {
            $e_msg = $this->_error_msg('Error creating database: '.$this->mysqli->error);
            return $e_msg;
        }
    }

    // drop database
    public function drop_database($dbname) {
        if( !$dbname ) {
            $e_msg = "Database name is required";
            die($e_msg);
        }
        $sql = "drop database `{$dbname}`";
        if($this->mysqli->query($sql)) {
            $s_msg = "Database dropped successfully";
            return $s_msg;
        } else {
            $e_msg = $this->get_error_msg('Error dropping database');
            return $e_msg;
        }
    }

    // create table
    public function create_table($create_sql) {

        if($create_sql) {
            if( !$this->mysqli->query($create_sql) ) {
                die("Error creating table: ".$create_sql);
            } else {
                echo "Table created successfully";
            }
        } else {
            return false;
        }
    }

    // change the storage engine of an existing table
    public function change_engine($table_name,$engine_type) {
        $sql = "alter table `{$table_name}` engine=`{$engine_type}`";
        if( $this->mysqli->query($sql) ) {
            echo 'Table Engine changed successfully';
        } else {
            $e_msg = "Error changing table($table_name) engine";
            die($e_msg);
        }
    }

    // show status
    public function show_status($table_name, $specific_columns=null) {
        $info_columns = [
            'TABLE_CATALOG',
            'TABLE_SCHEMA',
            'TABLE_NAME',
            'TABLE_TYPE',
            'ENGINE',
            'VERSION',
            'ROW_FORMAT',
            'TABLE_ROWS',
            'AVG_ROW_LENGTH',
            'DATA_LENGTH',
            'MAX_DATA_LENGTH',
            'INDEX_LENGTH',
            'DATA_FREE',
            'AUTO_INCREMENT',
            'CREATE_TIME',
            'UPDATE_TIME',
            'CHECK_TIME',
            'TABLE_COLLATION',
            'CHECKSUM',
            'CREATE_OPTIONS',
            'TABLE_COMMENT'
        ];
        if($specific_columns==null) {
            $info_columns = implode(',', $info_columns);
        } else {
            if(is_array($specific_columns)) {
                $info_columns = implode(',', $info_columns);
            } else {
                $info_columns = $info_columns;
            }
        }
        $sql = "select {$info_columns} from information_schema.tables where table_schema=DATABASE() and table_name='{$table_name}'";
        if($results = $this->mysqli->query($sql)) {
            // return arrays
            $row = $results->fetch_assoc();
            $results->free();
        } else {
            return false;
        }
        return $row;
    }

    // insert data
    public function insert($table_name, $keys, $values) {
        // sql: insert into(name1,name2,name3) values($value1,$value2,$value3),($value11,$value22,$value33);
        $sql = "insert into `{$table_name}`(".implode(',', $keys).") values";

        // if $batch == true;
        $rows = null;
        if(count($keys) === count($values[0])) {
            $rows = $values;
        } else {
            $rows[] = $values;
        }
        $insert_data = implode(',',array_map(function($x){
            return '(\''.implode("','",$x).'\')';
        },$rows));

        $sql .= $insert_data;

        if($result = $this->mysqli->query($sql)) {
            $first_insert_id=$this->mysqli->insert_id;
            $affected_rows = $this->mysqli->affected_rows;
            return $this->last_insert_id = $first_insert_id+$affected_rows-1;
        } else {
            return $result;
        }
    }


    // get columns from table
    public function get_columns($tablename, $detailed=null) {
        $sql = 'desc '."`{$tablename}`";
        if($result = $this->mysqli->query($sql)) {
            $fields = [];
            while($field = $result->fetch_assoc()) {
                $fields[] = $field;
            }
        } else {
            return false;
        }
        if($detailed==null) {
            // return array_map(function($arr){
            //     return $arr['Field'];
            // },$fields);
            // OR
            return array_column($fields, 'Field');
        } else {
            return $fields;
        }
    }

    // singleton pattern
    public static function get_instance() {
        if( !(self::$instance instanceof Mysql_db) ) {
            self::$instance = new self(self::$hostname, self::$username, self::$password, self::$database);
        }
        return self::$instance;
    }

    // destruct
    public function __destruct() {
        $this->mysqli->close();
    }
}

// $m = new Mysql_db('localhost', 'root', 'root', 'ecshop');
// // create database;
// echo $m->create_database('z');
// drop database;
// echo $m->drop_database('z');
// // create table;
// $create_sql = <<<CREATE_A
// create table `a`(
//     `id` int unsigned not null primary key auto_increment,
//     `name` char(30) not null default '',
//     `pwd` char(30) not null default '',
//     `age` int(3) unsigned not null default 0
// )engine=innodb default charset=utf8;
// CREATE_A;
// $m->create_table($create_sql);
// // change engine type
// $m->change_engine('a', 'myisam');
// show specific table status
// $info = $m->show_status('a');
// p($info);
// get columns from specific table
// $columns = $m->get_columns('a');
// p($columns);
// // get client info
// $client_info = $m->client_info;
// p($client_info);
// $server_info = $m->server_info;
// p($server_info);
// // server version
// p($m->server_version);
// p($m->client_version);
// $m->age = 7;
// p($m->age);
// insert data to specific table

// ---------------------------------
// $r = $m->insert(
//     'a',
//     ['name','pwd','age'],
//     [
//         ['Batch1', '111', 14],
//         ['Batch2', '233', 24],
//         ['Batch3', '355', 34],
//         ['Batch4', '466', 44],
//         ['Batch5', '588', 54],
//         ['Batch6', '699', 64],
//     ]
//     );
// p($r, 1);
// p($m->last_insert_id,1);
// -----------------------------------

// 工厂模式：一个新类--工厂类，这个类中的某个静态方法“负责”创建类
class Factory {// 这是一个工厂类
    // 生成mysqli_db对象
    public static function create_Mysql_db($hostname, $username, $password, $database) {
        // // 工厂模式
        // $db = new \database\Mysql_db($hostname, $username, $password, $database);
        // return $db;

        // 工厂模式和单例模式结合
        $db = new \database\Mysql_db($hostname, $username, $password, $database);
        return $db::get_instance();
    }
}
$db = Factory::create_Mysql_db('localhost', 'root', 'root', 'ecshop');
// $columns = $db->get_columns('a', 1);
// p($columns);
// $r = $db->insert(
//     'a', ['name', 'pwd', 'age'],
//     [
//         ['Zell', 'fuc', 30]
//     ]
// );
// p($r, 1);