db.class的实现类

单例类，能操作数据库，能拼接sql语句，能写入日志

<?php

class mysql extends db{
    private static $ins=null;
    private $conn=null;
    private $conf=array();
    //单例模式

    protected function __construct(){
        $this->conf=conf::getIns();

        $this->connect($this->conf->host,$this->conf->user,$this->conf->password);
        $this->select_db($this->conf->db);
        $this->setChar($this->conf->char);
    }
    public static function getIns(){
        if(self::$ins instanceof self){
            return self::$ins;
        }
        self::$ins=new self();
        return self::$ins;
    }
    public function connect($h,$u,$p){
        $this->conn=mysql_connect($h,$u,$p);
        if(!$this->conn){
            $err=new Exception('连接失败');
            throw $err;
        }
    }
    protected function select_db($db){
        $sql='use '.$db;
        $this->query($sql);
    }
    protected function setChar($char){
        $sql='set names '.$char;
        return $this->query($sql);
    }
    public function query($sql){
        if(defined('DEBUG')){
            log::write($sql);
        }

        $rs=mysql_query($sql,$this->conn);

        if(!$rs){
            log::write(mysql_error());
        }
        return $rs;
    }

    /*
    查询多行数据
    params $sql select型语句
    return array/boolean
    */
    public function getAll($sql){
        $rs=$this->query($sql);

        $arr=array();
        while(($row=mysql_fetch_assoc($rs))!==false){
            $arr[]=$row;
        }
        return $arr;
    }

    /*
    查询单行数据
    params $sql select型语句
    return array/boolean
    */
    public function getRow($sql){
         $rs=$this->query($sql);

        return mysql_fetch_assoc($rs);
    }

    /*
    查询单个数据
    params $sql select型语句
    return array/boolean
    */
    public function getOne($sql){
        $rs=$this->query($sql);
        $row=mysql_fetch_row($rs);
        return $row[0];
    }
    //返回影响的行数
    public function affected_rows(){
        return mysql_affected_rows($this->conn);
    }
    //返回最新的auto_increment列的自增长的值
    public function insert_id(){
        return mysql_insert_id($this->conn);
    }
    /*

    自动执行insert/update语句
    params $sql select型语句
    return array/boolean
    $this->autoExecute('user',array('username'=>'zhangsan','email'=>'zhang@123.com'),'insert');
    将自动形成 insert into user (username,email) values ('zhangsan','zhang@123.com');
    */
    public function autoExecute($table,$arr,$mode='insert',$where=' where 1 limit 1'){
        if(!is_array($arr)){
            return false;
        }

        if($mode=='update'){
            $sql='update '.$table.' set ';
            foreach ($arr as $k => $v) {
                $sql.=$k."= '". $v ."',";
            }
            $sql=rtrim($sql,',');
            $sql.=$where;

            return $this->query($sql);
        }

        $sql='insert into '.$table.' ('.implode(',',array_keys($arr)).')';
        $sql.=' values (\'';
        $sql.=implode("','",array_values($arr));
        $sql .='\')';

        return $this->query($sql);
    }
}
?>