封装pdo类

<?php


//使用pdo连接数据库 封装增删改查

class DB{

//定义私有属性
private $host;
private $port;
private $username;
private $password;
private $dbname;
private $charset;
private $dbtype;
private $pdo;

//定义构造函数自动加载配置文件
function __construct(){
//加载配置文件
include_once('./config/config.php');

//给属性赋值
$this->dbtype = $config['db'];
        $this->host  = $config['host'];
        $this->username = $config['username'];
        $this->password = $config['password'];
        $this->charset = $config['charset'];
        $this->port = $config['port'];
        $this->dbname = $config['dbname'];

//pdo连接数据库
$this->pdo = new PDO("$this->dbtype:host=$this->host;dbname=$this->dbname","$this->username","$this->password");
//发送编码
$this->pdo->query("set names $this->charset");
    }

/**
     *   定义执行查询sql语句的方法
     *   参数： 查询sql语句
     *   返回： 二维关联数组
     */
public function query($sql){
        $res = $this->pdo->query($sql);
        $res->setFetchMode(PDO::FETCH_ASSOC);
        $arr = $res->fetchAll();
return $arr;
    }


/**
     *   查询一行记录的方法
     *   参数：表名  条件(不包含where)
     *   返回：一维关联数组
     */
public function getRow($tablename,$where){
//组装sql语句
$sql = "select * from $tablename where $where";
//查询
$res = $this->pdo->query($sql);
        $res->setFetchMode(PDO::FETCH_ASSOC);
        $arr = $res->fetch();
return $arr;
    }


/**
     *   查询全部记录
     *   参数：表名
     *   返回：二维关联数组
     */
public function getAll($tablename){
        $res = $this->pdo->query("select * from $tablename");
        $res->setFetchMode(PDO::FETCH_ASSOC);
        $arr = $res->fetchAll();
return $arr;
    }

/**
     *   查询某个字段
     *   参数： 字段名(多个的话用逗号隔开) 表名 条件（不含where）
     *   返回： 二维关联数组
     */
public function getOne($column,$tablename,$where="1"){
//拼接sql语句
$sql = "select $column from $tablename where $where";
        $rs = $this->pdo->query($sql);
        $rs->setFetchMode(PDO::FETCH_ASSOC);
//$col = $rs->fetchColumn();
$col = $rs->fetchAll();
return  $col;
    }


/**
     *   查询最后一次插入的数据
     *   参数：表名
     *   返回：数组
    */
public function getlastone($tablename){
        $sql = "select * from $tablename where id=(select max(id) from $tablename)";
        $res = $this->pdo->query($sql);
        $res->setFetchMode(PDO::FETCH_ASSOC);
        $arr = $res->fetch();
return $arr;
    }


/**
     *  向数据库中添加一条信息
     *  参数：表名 一维关联数组
     *  返回: 布尔值
     */
public function insert($tablename,$arr){
//拿到数组之后先处理数组  过滤字段
        //取出表中的字段
$sql = "select COLUMN_NAME from information_schema.COLUMNS where table_name = '$tablename' and table_schema ='$this->dbname'";
        $columns = $this->pdo->query($sql);
        $columns->setFetchMode(PDO::FETCH_ASSOC);
        $columns = $columns->fetchAll();
        $cols = array(); //存储表中的全部字段
foreach($columns as $key=>$val){
            $cols[] = $val['COLUMN_NAME'];
        }
//将要入库的数组进行键值分离
$keys = array();
        $values = '';
foreach($arr as $k=>$v){
if(!in_array($k,$cols)){
unset($arr[$k]);
            }else{
                $keys[] = $k;
                $values .= "'".$v."',";
            }
        }
        $column = implode(',',$keys);
        $values = substr($values,0,-1);
//拼接sql语句
$sql = "insert into $tablename($column) values ($values)";
        $res = $this->pdo->exec($sql);
return $res;
    }


/**
     *   删除数据 其实就是改变字段值使之不被查询
     *   参数：表名 条件(不含where)
     *   返回：布尔
    */
public function delete($tablename,$where){
        $sql = "update $tablename set is_del=1 where $where";
        $res = $this->pdo->exec($sql);
return $res;
    }


/**
     *   修改数据
     *   参数：表名  要修改的数据的数组
     *   返回：布尔
    */
public function update($tablename,$arr,$where){
//处理传过来的数组
$str = "";
foreach($arras $k=>$v){
            $str .= "$k='".$v."',";
        }
//截取字符串
$str = substr($str,0,-1);
//拼接sql语句
$sql = "update $tablename set $str where $where";
        $res = $this->pdo->exec($sql);
return $res;
    }
}