MySQL backup

I originally thought about using SHOW CREATE TABLE + ergodic for backup, but I found that if the Table has comments and they are garbled, the script coming out of SHOW CREATE TABLE will be missing a symbol. So there is this version.

	class MysqlExport{

		/**
		 * database connect
*/
		private $_db;

		private $_resource;

		/**
		 * create table structure sql
*/
		private $_create_table = '';

		public function __construct($host = '', $user = '', $pass = '', $db = '', $port = 3306) {
			if (empty($host) || empty($user)) {

			} else {
				$this->real_connect($host, $user, $pass, $db, $port);
			}
		}

		public function init() {
			return $this;
		}

		/**
 * Connect to database
*/
		public function real_connect($host, $user, $pass, $db = '', $port = 3306) {
			$this->_db = mysql_connect($host . ':' . $port, $user, $pass);
			if ($db) {
				$this->select_db($db);
			}
			return $this->init();
		}

		/**
 * Select database
*/
		public function select_db($db) {
			if (mysql_select_db($db, $this->_db)) {
				return true;
			}
		}

		/**
 * Query statement
*/
		public function query($sql) {
			if ($this->_db) {
				if ($this->_resource = mysql_query($sql, $this->_db)) {
					return $this->init();
				}
			}
			throw new Exception($this->get_error());
		}

		/**
 * Get the result set
*/
		public function fetch_array($arg = MYSQL_BOTH) {
			$result = array();
			if ($this->_resource && !mysql_errno($this->_db)) {
				while ($rs = mysql_fetch_array($this->_resource, $arg)) {
					$result[] = $rs;
				}
			}
			return $result;
		}

		/**
 * Get error
*/
		public function get_error() {
			return mysql_errno($this->_db) . ": " . mysql_error($this->_db). "n";
		}

		/**
 *Show data table
*/
		public function show_tables($table = '') {
			$sql = "SHOW TABLES";
			$sql .= $table ? " LIKE '{$table}'" : '';
			$result = $this->query($sql)->fetch_array(MYSQL_ASSOC);
			return $result;
		}

		/**
 *Show data table fields
*/
		public function show_columns($table) {
			if (empty($table)) {
				return array();
			}
			$sql = "SHOW FULL COLUMNS FROM {$table}";
			$result = $this->query($sql)->fetch_array(MYSQL_ASSOC);
			return $result;
		}

		/**
 * Show data table status
*/
		public function show_table_status($table) {
			if (empty($table)) {
				return array();
			}
			$result = $this->query("SHOW TABLE STATUS LIKE '{$table}'")->fetch_array(MYSQL_ASSOC);
			$result = reset($result);
			return $result;
		}

		/**
 *Show data table structure
*/
		public function show_create_table($table) {
			if (empty($table)) {
				return '';
			}
			$this->_create_table  = "CREATE TABLE IF NOT EXISTS `{$table}`(" . PHP_EOL;
			$table_status = $this->show_table_status($table);
			$columns = $this->show_columns($table);

			foreach ($columns AS $col) {
				$this->_create_table .= "`{$col['Field']}` {$col['Type']} NOT NULL {$col['Extra']}," . PHP_EOL;
			}

			$this->_create_table .= $this->create_indexSyntax($table);

			$char = substr($table_status['Collation'], 0, strpos($table_status['Collation'], '_'));
			$table_status['Auto_increment'] = $table_status['Auto_increment'] ? $table_status['Auto_increment'] : 0;
			$this->_create_table .= ")Engine={$table_status['Engine']} AUTO_INCREMENT={$table_status['Auto_increment']} DEFAULT CHARSET={$char};" . str_repeat(PHP_EOL, 3);

			return $this->_create_table;
		}

		/**
 *Show trigger
*/
		public function show_constraint($db_name) {
			if (empty($db_name)) {
				return array();
			}
			$sql = "SELECT a.CONSTRAINT_NAME AS constrint_name, a.TABLE_name AS table_name, a.COLUMN_NAME AS column_name, a.REFERENCED_TABLE_NAME as referenced_table_name, a.REFERENCED_COLUMN_NAME AS referenced_column_name, b.UPDATE_RULE as update_rule, b.DELETE_RULE AS delete_rule FROM information_schema.KEY_COLUMN_USAGE AS a LEFT JOIN information_schema.REFERENTIAL_CONSTRAINTS AS b ON a.constraint_name=b.constraint_name WHERE a.constraint_schema = '{$db_name}' AND a.POSITION_IN_UNIQUE_CONSTRAINT = 1";
			$result = $this->query($sql)->fetch_array(MYSQL_ASSOC);
		}

		/**
 * Show index
*/
		public function show_index($table) {
			if (empty($table)) {
				return array();
			}
			$sql = "SHOW INDEX FROM {$table}";
			$result = $this->query($sql)->fetch_array(MYSQL_ASSOC);
			return $result;
		}

		/**
 *Show database structure
*/
		public function show_database_char() {
			$sql = "SHOW VARIABLES LIKE 'character_set_database'";
			$char = $this->query($sql)->fetch_array(MYSQL_ASSOC);
			return reset($char);
		}

		/**
 * Create index syntax
*/
		public function create_indexSyntax($table) {
			if (empty($table)) {
				return array();
			}
			$indexing = $this->show_index($table);
			$syntax = array();
			$indexSyntax = array();
			foreach ($indexing as $index) {
				$syntax[$index['Index_type']][$index['Key_name']][] = $index['Column_name'];
			}

			foreach ($syntax as $index_type => $index_value) {
				foreach ($index_value as $key_name => $columns) {
					if ($key_name == 'PRIMARY') {
						$indexSyntax[] = 'PRIMARY KEY (`' . implode("`,`", $columns) . '`)';
					} else {
						if ($index_type == 'FULLTEXT') {
							$indexSyntax[] = "FULLTEXT KEY `{$key_name}` (`" . implode("`,`", $columns) . '`)';
						} else{
							$indexSyntax[] = "KEY `{$key_name}` USING {$index_type} (`" . implode("`,`", $columns) . '`)';
						}
					}
				}
			}

			return implode(',' . PHP_EOL, $indexSyntax) . PHP_EOL;
		}

		/**
 * Create insert syntax
*/
		public function create_insertSyntax($table) {
			if (empty($table)) {
				return '';
			}
			$sql = "SELECT * FROM {$table}";
			$result = $this->query($sql)->fetch_array(MYSQL_ASSOC);
			$insertStr = '';
			if ($result) {
				$first = reset($result);
				$key = implode('`,`', array_keys($first));
				$insert = "INSERT INTO `{$table}` (`{$key}`) VALUES ";
				$valuesStr = array();
				foreach ($result as $value) {
					$values = array();
					foreach ($value as $v) {
						$v = mysql_real_escape_string($v);
						$values[] = preg_replace("#\+#", "\", $v);
					}
					$valuesStr[] = "('" . implode("','", $values) . "')";
				}
				$valuesStr = array_chunk($valuesStr, 5000);
				foreach ($valuesStr as $str) {
					$insertStr .= $insert . implode(',', $str) . ';' . PHP_EOL;
				}

			}
			return $insertStr . str_repeat(PHP_EOL, 3);
		}

	}

	$export = '';
	$test = new MysqlExport('localhost', 'root', '', 'pm_cms');
	$char = $test->show_database_char();
	$test->query("SET NAMES {$char['Value']}");
	$tables = $test->show_tables();
	foreach ($tables as $table) {
		list($table_name)  = array_values($table);
		$export .= $test->show_create_table($table_name);
		$export .= $test->create_insertSyntax($table_name);
	}
	$fp = fopen('pm_cms.sql', 'w');
	fwrite($fp, $export);
	fclose($fp);
?>