<?php
namespace ns;
use PDO;
class DB
{
protected $db;//数据库对象
protected $table;//表名
protected $field;//字段名
protected $limit;//限制
protected $opt =[];//具体操作
// 链接数据库
public function __construct($dsn,$username,$password)
{
$this->db= new PDO($dsn,$username,$password);
}
// 表名赋值
public function table($table)
{
$this->table = $table;
return $this;
}
// 字段赋值
public function field($field)
{
$this->field = $field;
return $this;
}
//分页操作
public function page($page =1)
{
$this->opt['offset']=' OFFSET '.($page -1 )*$this->limit;
return $this;
}
//限制设置
public function limit($limit = 10)
{
$this->limit = $limit;
$this->opt['limit'] = "LIMIT $limit";
return $this;
}
//查询条件
public function where($where = '')
{
$this->opt['where']= "WHERE $where";
return $this;
}
// 查询
public function select()
{
$sql = 'SELECT '. $this->field . ' FROM '.$this->table;
$sql.=$this->opt['where'] ?? null;
$sql.=$this->opt['limit'] ?? null;
$sql.=$this->opt['offset'] ?? null;
$stmt = $this->db->prepare($sql);
$stmt->execute();
$this->opt['where'] = null;
return $stmt->fetchAll();
}
// 插入操作
public function insert($data)
{
$str='';
foreach ($data as $key=>$value)
{
$str.=$key.'= "'.$value.'",';
}
$sql = 'INSERT '.$this->table . 'SET '.rtrim($str,',');
$stmt=$this->db->prepare($sql);
$stmt->execute();
$this->opt['where'] = null;
return $stmt->rowCount();
}
//更新操作
public function updata($data)
{
$str='';
foreach($data as $key=>$value){
$str.=$key.'= "'.$value.'",';
}
$sql= 'UPDATE '.$this->table.'SET'.rtrim($str,',');
$stmt=$this->db->prepare($sql);
$stmt->execute();
$this->opt['where']=null;
return $stmt->rowCount();
}
//删除操作
public function delete()
{
$sql = 'DELETE FROM ' .$this->table;
$sql.= $this->opt['where']??die('禁止无条件删除');
$stmt= $this->db->prepare($sql);
$stmt->execute();
$this->opt['where']=null;
return $stmt->rowCount();
}
}
