PHP database is based on PDO operation class (mysql)

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PHP The database is based on PDO operation class (mysql)

## This is an operation class about Mysql that I found on the Internet. It is very suitable for beginners to use

<?phpclass  Mysql {        protected static $_dbh = null; //静态属性,所有数据库实例共用,避免重复连接数据库
        protected $_dbType = &#39;mysql&#39;;        protected $_pconnect = true; //是否使用长连接
        protected $_host = &#39;localhost&#39;;        protected $_port = 3306;        protected $_user = &#39;root&#39;;        protected $_pass = &#39;&#39;;        protected $_dbName = null; //数据库名
        protected $_sql = false; //最后一条sql语句
        protected $_where = &#39;&#39;;        protected $_order = &#39;&#39;;        protected $_limit = &#39;&#39;;        protected $_field = &#39;*&#39;;        protected $_clear = 0; //状态，0表示查询条件干净，1表示查询条件污染
        protected $_trans = 0; //事务指令数 

        /**
         * 初始化类
         * @param array $conf 数据库配置         */
        public function __construct(array $conf) {            class_exists(&#39;PDO&#39;) or die("PDO: class not exists.");            $this->_host = $conf['host'];            $this->_port = $conf['port'];            $this->_user = $conf['user'];            $this->_pass = $conf['password'];            $this->_dbName = $conf['dbname'];            //连接数据库
            if ( is_null(self::$_dbh) ) {                $this->_connect();
            }
        }        /**
         * 连接数据库的方法         */
        protected function _connect() {            $dsn = $this->_dbType.':host='.$this->_host.';port='.$this->_port.';dbname='.$this->_dbName;            //持久化连接
            $options = $this->_pconnect ? array(PDO::ATTR_PERSISTENT=>true) : array();            try { 
                $dbh = new PDO($dsn, $this->_user, $this->_pass, $options);                $dbh->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);  //设置如果sql语句执行错误则抛出异常，事务会自动回滚
                $dbh->setAttribute(PDO::ATTR_EMULATE_PREPARES, false); //禁用prepared statements的仿真效果(防SQL注入)
            } catch (PDOException $e) { 
                die('Connection failed: ' . $e->getMessage());
            }            $dbh->exec('SET NAMES utf8');
            self::$_dbh = $dbh;
        }        /** 
        * 字段和表名添加 `符号
        * 保证指令中使用关键字不出错 针对mysql 
        * @param string $value 
        * @return string 
        */
        protected function _addChar($value) { 
            if ('*'==$value || false!==strpos($value,'(') || false!==strpos($value,'.') || false!==strpos($value,'`')) { 
                //如果包含* 或者 使用了sql方法 则不作处理 
            } elseif (false === strpos($value,'`') ) { 
                $value = '`'.trim($value).'`';
            } 
            return $value; 
        }        /** 
        * 取得数据表的字段信息 
        * @param string $tbName 表名
        * @return array 
        */
        protected function _tbFields($tbName) {            $sql = 'SELECT COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME="'.$tbName.'" AND TABLE_SCHEMA="'.$this->_dbName.'"';            $stmt = self::$_dbh->prepare($sql);            $stmt->execute();            $result = $stmt->fetchAll(PDO::FETCH_ASSOC);            $ret = array();            foreach ($result as $key=>$value) {                $ret[$value['COLUMN_NAME']] = 1;
            }            return $ret;
        }        /** 
        * 过滤并格式化数据表字段
        * @param string $tbName 数据表名 
        * @param array $data POST提交数据 
        * @return array $newdata 
        */
        protected function _dataFormat($tbName,$data) {            if (!is_array($data)) return array();            $table_column = $this->_tbFields($tbName);            $ret=array();            foreach ($data as $key=>$val) {                if (!is_scalar($val)) continue; //值不是标量则跳过
                if (array_key_exists($key,$table_column)) {                    $key = $this->_addChar($key);                    if (is_int($val)) { 
                        $val = intval($val); 
                    } elseif (is_float($val)) { 
                        $val = floatval($val); 
                    } elseif (preg_match('/^\(\w*(\+|\-|\*|\/)?\w*\)$/i', $val)) {                        // 支持在字段的值里面直接使用其它字段 ,例如 (score+1) (name) 必须包含括号
                        $val = $val;
                    } elseif (is_string($val)) { 
                        //将字符串中的单引号（'）、双引号（"）、反斜线（\）与 NUL（NULL 字符转义
                        $val = '"'.addslashes($val).'"';
                    }                    $ret[$key] = $val;
                }
            }            return $ret;
        }        /**
        * 执行查询 主要针对 SELECT, SHOW 等指令
        * @param string $sql sql指令 
        * @return mixed 
        */
        protected function _doQuery($sql='') {            $this->_sql = $sql;            $pdostmt = self::$_dbh->prepare($this->_sql); //prepare或者query 返回一个PDOStatement
            $pdostmt->execute();            $result = $pdostmt->fetchAll(PDO::FETCH_ASSOC);            return $result;
        }        /** 
        * 执行语句 针对 INSERT, UPDATE 以及DELETE,exec结果返回受影响的行数
        * @param string $sql sql指令 
        * @return integer 
        */
        protected function _doExec($sql='') {            $this->_sql = $sql;            return self::$_dbh->exec($this->_sql);
        }        /** 
        * 执行sql语句，自动判断进行查询或者执行操作 
        * @param string $sql SQL指令 
        * @return mixed 
        */
        public function doSql($sql='') {            $queryIps = 'INSERT|UPDATE|DELETE|REPLACE|CREATE|DROP|LOAD DATA|SELECT .* INTO|COPY|ALTER|GRANT|REVOKE|LOCK|UNLOCK'; 
            if (preg_match('/^\s*"?(' . $queryIps . ')\s+/i', $sql)) { 
                return $this->_doExec($sql);
            }            else {                //查询操作
                return $this->_doQuery($sql);
            }
        }        /** 
        * 获取最近一次查询的sql语句 
        * @return String 执行的SQL 
        */
        public function getLastSql() { 
            return $this->_sql;
        }        /**
         * 插入方法
         * @param string $tbName 操作的数据表名
         * @param array $data 字段-值的一维数组
         * @return int 受影响的行数         */
        public function insert($tbName,array $data){            $data = $this->_dataFormat($tbName,$data);            if (!$data) return;            $sql = "insert into ".$tbName."(".implode(',',array_keys($data)).") values(".implode(',',array_values($data)).")";            return $this->_doExec($sql);
        }        /**
         * 删除方法
         * @param string $tbName 操作的数据表名
         * @return int 受影响的行数         */
        public function delete($tbName) {            //安全考虑,阻止全表删除
            if (!trim($this->_where)) return false;            $sql = "delete from ".$tbName." ".$this->_where;            $this->_clear = 1;            $this->_clear();            return $this->_doExec($sql);
        }        /**
         * 更新函数
         * @param string $tbName 操作的数据表名
         * @param array $data 参数数组
         * @return int 受影响的行数         */
        public function update($tbName,array $data) {            //安全考虑,阻止全表更新
            if (!trim($this->_where)) return false;            $data = $this->_dataFormat($tbName,$data);            if (!$data) return;            $valArr = '';            foreach($data as $k=>$v){                $valArr[] = $k.'='.$v;
            }            $valStr = implode(',', $valArr);            $sql = "update ".trim($tbName)." set ".trim($valStr)." ".trim($this->_where);            return $this->_doExec($sql);
        }        /**
         * 查询函数
         * @param string $tbName 操作的数据表名
         * @return array 结果集         */
        public function select($tbName='') {            $sql = "select ".trim($this->_field)." from ".$tbName." ".trim($this->_where)." ".trim($this->_order)." ".trim($this->_limit);            //echo $sql;
            $this->_clear = 1;            $this->_clear();            return $this->_doQuery(trim($sql));
        }        /**
         * @param mixed $option 组合条件的二维数组，例：$option['field1'] = array(1,'=>','or')
         * @return $this         */
        public function where($option) {            if ($this->_clear>0) $this->_clear();            $this->_where = ' where ';            $logic = 'and';            if (is_string($option)) {                $this->_where .= $option;
            }            elseif (is_array($option)) {                foreach($option as $k=>$v) {                    if (is_array($v)) {                        $relative = isset($v[1]) ? $v[1] : '=';                        $logic    = isset($v[2]) ? $v[2] : 'and';                        $condition = ' ('.$this->_addChar($k).' '.$relative.' '.$v[0].') ';
                    }                    else {                        $logic = 'and';                        $condition = ' ('.$this->_addChar($k).'='.$v.') ';
                    }                    $this->_where .= isset($mark) ? $logic.$condition : $condition;                    $mark = 1;
                }
            }            return $this;
        }        /**
         * 设置排序
         * @param mixed $option 排序条件数组 例:array('sort'=>'desc')
         * @return $this         */
        public function order($option) {            if ($this->_clear>0) $this->_clear();            $this->_order = ' order by ';            if (is_string($option)) {                $this->_order .= $option;
            }            elseif (is_array($option)) {                foreach($option as $k=>$v){                    $order = $this->_addChar($k).' '.$v;                    $this->_order .= isset($mark) ? ','.$order : $order;                    $mark = 1;
                }
            }            return $this;
        }        /**
         * 设置查询行数及页数
         * @param int $page pageSize不为空时为页数，否则为行数
         * @param int $pageSize 为空则函数设定取出行数，不为空则设定取出行数及页数
         * @return $this         */
        public function limit($page,$pageSize=null) {            if ($this->_clear>0) $this->_clear();            if ($pageSize===null) {                $this->_limit = "limit ".$page;
            }            else {                $pageval = intval( ($page - 1) * $pageSize);                $this->_limit = "limit ".$pageval.",".$pageSize;
            }            return $this;
        }        /**
         * 设置查询字段
         * @param mixed $field 字段数组
         * @return $this         */
        public function field($field){            if ($this->_clear>0) $this->_clear();            if (is_string($field)) {                $field = explode(',', $field);
            }            $nField = array_map(array($this,'_addChar'), $field);            $this->_field = implode(',', $nField);            return $this;
        }        /**
         * 清理标记函数         */
        protected function _clear() {            $this->_where = '';            $this->_order = '';            $this->_limit = '';            $this->_field = '*';            $this->_clear = 0;
        }        /**
         * 手动清理标记
         * @return $this         */
        public function clearKey() {            $this->_clear();            return $this;
        }        /**
        * 启动事务 
        * @return void 
        */
        public function startTrans() { 
            //数据rollback 支持 
            if ($this->_trans==0) self::$_dbh->beginTransaction();            $this->_trans++; 
            return; 
        }        /** 
        * 用于非自动提交状态下面的查询提交 
        * @return boolen 
        */
        public function commit() {            $result = true;            if ($this->_trans>0) { 
                $result = self::$_dbh->commit(); 
                $this->_trans = 0;
            } 
            return $result;
        }        /** 
        * 事务回滚 
        * @return boolen 
        */
        public function rollback() {            $result = true;            if ($this->_trans>0) {                $result = self::$_dbh->rollback();                $this->_trans = 0;
            }            return $result;
        }        /**
        * 关闭连接
        * PHP 在脚本结束时会自动关闭连接。        */
        public function close() {            if (!is_null(self::$_dbh)) self::$_dbh = null;
        }

}

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