数据库链式调用封装-KeepStudy

数据库链式调用封装

```php
<?php
	header("Content-Type:text/html;charset=utf-8");

/**
	 *php操作mysql的工具类
	 */
	class Db{
		private $_db = null;//数据库连接句柄
		private $_table = null;//表名
		private $_where = null;//where条件
		private $_order = null;//order排序
		private $_limit = null;//limit限定查询
		private $_group = null;//group分组
		private $_configs = array(
			'hostname' => 'localhost',
			'dbname'   => 'test',
			'username' => 'root',
			'password' => '1234'
		);//数据库配置

/**
		 * 构造函数，连接数据库
		 */
		public function __construct(){
			$link = $this->_db;
			if(!$link){
				$db = mysqli_connect($this->_configs['hostname'],$this->_configs['username'],$this->_configs['password'],$this->_configs['dbname']);
				mysqli_query($db,"set names utf8");
				if(!$db){
					$this->ShowException("错误信息".mysqli_connect_error());
				}
				$this->_db = $db;
			}
		}

/**
		 * 获取所有数据
		 *
		 * @param      <type>   $table  The table
		 *
		 * @return     boolean  All.
		 */
		public function getAll($table=null){
			$link = $this->_db;
			if(!$link)return false;
			$sql = "SELECT * FROM {$table}";
			$data = mysqli_fetch_all($this->execute($sql));
			return $data;
		}

public function table($table){
			$this->_table = $table;
			return $this;
		}

/**
		 * 实现查询操作
		 *
		 * @param      string   $fields  The fields
		 *
		 * @return     boolean  ( description_of_the_return_value )
		 */
		public function select($fields="*"){
			$fieldsStr = '';
			$link = $this->_db;
			if(!$link)return false;
			if(is_array($fields)){
				$fieldsStr = implode(',', $fields);
			}elseif(is_string($fields)&&!empty($fields)){
				$fieldsStr = $fields;
			}
			$sql = "SELECT {$fields} FROM {$this->_table} {$this->_where} {$this->_order} {$this->_limit}";
			$data = mysqli_fetch_all($this->execute($sql));
			return $data;
		}

/**
		 * order排序
		 *
		 * @param      string   $order  The order
		 *
		 * @return     boolean  ( description_of_the_return_value )
		 */
		public function order($order=''){
			$orderStr = '';
			$link = $this->_db;
			if(!$link)return false;
			if(is_string($order)&&!empty($order)){
				$orderStr = "ORDER BY ".$order;
			}
			$this->_order = $orderStr;
			return $this;
		}

/**
		 * where条件
		 *
		 * @param      string  $where  The where
		 *
		 * @return     <type>  ( description_of_the_return_value )
		 */
		public function where($where=''){
			$whereStr = '';
			$link = $this->_db;
			if(!$link)return $link;
			if(is_array($where)){
				foreach ($where as $key => $value) {
					if($value == end($where)){
						$whereStr .= "`".$key."` = '".$value."'";
					}else{
						$whereStr .= "`".$key."` = '".$value."' AND ";
					}
				}
				$whereStr = "WHERE ".$whereStr;
			}elseif(is_string($where)&&!empty($where)){
				$whereStr = "WHERE ".$where;
			}
			$this->_where = $whereStr;
			return $this;
		}

/**
		 * group分组
		 *
		 * @param      string   $group  The group
		 *
		 * @return     boolean  ( description_of_the_return_value )
		 */
		public function group($group=''){
			$groupStr = '';
			$link = $this->_db;
			if(!$link)return false;
			if(is_array($group)){
				$groupStr = "GROUP BY ".implode(',',$group);
			}elseif(is_string($group)&&!empty($group)){
				$groupStr = "GROUP BY ".$group;
			}
			$this->_group = $groupStr;
			return $this;
		}

/**
		 * limit限定查询
		 *
		 * @param      string  $limit  The limit
		 *
		 * @return     <type>  ( description_of_the_return_value )
		 */
		public function limit($limit=''){
			$limitStr = '';
			$link = $this->_db;
			if(!$link)return $link;
			if(is_string($limit)||!empty($limit)){
				$limitStr = "LIMIT ".$limit;
			}elseif(is_numeric($limit)){
				$limitStr = "LIMIT ".$limit;
			}
			$this->_limit = $limitStr;
			return $this;
		}

/**
		 * 执行sql语句
		 *
		 * @param      <type>   $sql    The sql
		 *
		 * @return     boolean  ( description_of_the_return_value )
		 */
		public function execute($sql=null){
			$link = $this->_db;
			if(!$link)return false;
			$res = mysqli_query($this->_db,$sql);
			if(!$res){
				$errors = mysqli_error_list($this->_db);
				$this->ShowException("报错啦！<br/>错误号：".$errors[0]['errno']."<br/>SQL错误状态：".$errors[0]['sqlstate']."<br/>错误信息：".$errors[0]['error']);
				die();
			}
			return $res;
		}

/**
		 * 插入数据
		 *
		 * @param      <type>   $data   The data
		 *
		 * @return     boolean  ( description_of_the_return_value )
		 */
		public function insert($data){
			$link = $this->_db;
			if(!$link)return false;
			if(is_array($data)){
				$keys = '';
				$values = '';
				foreach ($data as $key => $value) {
					$keys .= "`".$key."`,";
					$values .= "'".$value."',";
				}
				$keys = rtrim($keys,',');
				$values = rtrim($values,',');
			}
			$sql = "INSERT INTO `{$this->_table}`({$keys}) VALUES({$values})";
			mysqli_query($this->_db,$sql);
			$insertId = mysqli_insert_id($this->_db);
			return $insertId;
		}

/**
		 * 更新数据
		 *
		 * @param      <type>  $data   The data
		 *
		 * @return     <type>  ( description_of_the_return_value )
		 */
		public function update($data){
			$link = $this->_db;
			if(!$link)return $link;
			if(is_array($data)){
				$dataStr = '';
				foreach ($data as $key => $value) {
					$dataStr .= "`".$key."`='".$value."',";
				}
				$dataStr = rtrim($dataStr,',');
			}
			$sql = "UPDATE `{$this->_table}` SET {$dataStr} {$this->_where} {$this->_order} {$this->_limit}";
			$res = $this->execute($sql);
			return $res;
		}

/**
		 * 删除数据
		 *
		 * @return     <type>  ( description_of_the_return_value )
		 */
		public function delete(){
			$link = $this->_db;
			if(!$link)return $link;
			$sql = "DELETE FROM `{$this->_table}` {$this->_where}";
			$res = $this->execute($sql);
			return $res;
		}

/**
		 * 异常信息输出
		 *
		 * @param      <type>  $var    The variable
		 */
		private function ShowException($var){
			if(is_bool($var)){
				var_dump($var);
			}else if(is_null($var)){
				var_dump(NULL);
			}else{
				echo "<pre style='position:relative;z-index:1000;padding:10px;border-radius:5px;background:#F5F5F5;border:1px solid #aaa;font-size:14px;line-height:18px;opacity:0.9;'>".print_r($var,true)."</pre>";
			}
		}

}
```

调用
```php
	$db = new Db();
	//查询操作
	var_dump($db->table('user')->where('id > 2')->order('id desc')->limit('2,4')->select());

//插入操作
	var_dump($db->table('user')->insert(array('username'=>'user','password'=>'pwd')));

//更新操作
	var_dump($db->table('user')->where('id = 1')->update(array('username'=>'user1','password'=>'pwd1')));

//删除操作
	var_dump($db->table('user')->where('id = 1')->delete());
```

顶部

PHP工具类

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