11月27日 - 数据库操作函数重写到 Db类中

数据库操作函数重写到 Db类中

代码：

  <?php
class Db{
    protected $table = null;
    public function __construct($dsn,$user,$password,$table){
        $this-> pdo = new PDO($dsn,$user,$password);
        $this->table =$table;
    }
    public function create($data){
        $sql = "INSERT INTO {$this->table} SET";
        if(is_array($data)){
            foreach ($data as $k=>$v){
                $sql .=$k.'="'. $v.'",';
            }
        }else{
            return false;
        }
        $sql = rtrim(trim($sql),',').';';
        $stmt = $this->pdo->prepare($sql);
    }
    public function read($where,$order,$limit=10,$fields='*'){
        //创建SQL语句
        $sql = 'SELECT ';
        if (is_array($fields)) {
            foreach ($fields as $field) {
                $sql .= $field.', ';
            }
        } else {
            $sql .= $fields;
        }
        $sql = rtrim(trim($sql),',');
        $sql .= '  FROM '.$this->table;
        //查询条件
        if(!empty($where)){
            $sql .= ' WHERE '.$where;
        }
        //排序条件
        if(!empty($order)) {
            $sql .= ' order by '.$order;
        }
        //分页条件
        if(!empty($limit)) {
            $sql .= ' limit '.$limit;
        }
        $sql .= ';';
        //创建PDO预处理对象
        $stmt = $this->pdo->prepare($sql);
        //执行查询操作
        if($stmt->execute()){
            if($stmt->rowCount()>0){
                $stmt->setFetchMode(PDO::FETCH_ASSOC);
                //返回一个二维数组
                return $stmt->fetchAll();
            }
        } else {
            return false;
        }
    }
    public function update($table,$data=[], $where=''){
        $sql = "UPDATE {$this->table} SET ";
        //组装修改语句
        if(is_array($data)){
            foreach ($data as $k=>$v) {
                $sql .= $k.'="'.$v.'", ';
            }
        }
        //去掉尾部逗号,并添加分号结束
        $sql = rtrim(trim($sql),',');
        //查询条件
        if(!empty($where)){
            $sql .= ' WHERE '.$where;
        }
        //创建PDO预处理对象
        $stmt = $this->pdo->prepare($sql);
        //执行新增操作
        if($stmt->execute()){
            if($stmt->rowCount()>0){
                return true;
            }
        } else {
            return false;
        }
    }
    public function delete($table,$where){
        $sql = "DELETE FROM {$this->table}  ";
        //查询条件
        if(!empty($where)){
            $sql .= ' WHERE '.$where;
        }
        //创建PDO预处理对象
        $stmt = $this->pdo->prepare($sql);
        //执行删除操作
        if($stmt->execute()){
            if($stmt->rowCount()>0){
                return true;
            }
        } else {
            return false;
        }
    }
}
$d = new Db('mysql:host=localhost;dbname=php2020','root','roottt','user');
$d->read('uid=1','age DESC');
print_r($d); 

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