2019年11月27日—用类重写PDO操作函数

<?php
// 把pdo写到类中
class Db
{
    public $dsn;
    public $username;
    public $password;
    public $pdo;
    public function __construct($dsn, $username, $password)
    {
        $this->dsn = $dsn;
        $this->username = $username;
        $this->password = $password;
//        return new PDO($this->dsn,$this->username,$this->password);
        $this->connect();
    }
    public function connect()
    {
        try {
            $this->pdo = new PDO($this->dsn, $this->username, $this->password);
        } catch (PDOException $e) {
            die(print_r($e->getMessage(), true));
        }
        return $this->pdo;
    }
    //新增操作
    public function insert($table, $data = [])
    {
        //连接sql数据库
        //组装sql语句
        $sql = "INSERT INTO {$table} SET ";
//        print_r($data);
        if (is_array($data) && !empty($data)) {
            foreach ($data as $k => $v) {
                $sql .= '`' . $k . '`="' . $v . '",';
            }
        } else {
            return false;
        }
        $sql = rtrim(trim($sql), ',') . ';';
//        print_r($sql);exit();
        //创建预处理对象
        $stmt = $this->pdo->prepare($sql);
        //执行sql操作
        $res = $stmt->execute();
        //返回操作结果
        if ($res) {
            if ($stmt->rowCount() > 0) {
                return '成功添加了' . $stmt->rowCount() . '条数据';
            } else {
                return '没有新增数据';
            }
        } else {
            return false;
        }
        //关闭sql链接
    }
    //修改操作
    public function update($table, $data = [], $where = '')
    {
        $sql = "UPDATE {$table} SET ";
        if (is_array($data) && !empty($data)) {
            foreach ($data as $k => $v) {
                $sql .= '`' . $k . '`="' . $v . '",';
            }
        } else {
            return false;
        }
        $sql = rtrim(trim($sql), ',') . ' ';
        if (!empty($where)) {
            $sql .= 'WHERE ' . $where . ';';
        } else {
            return false;
        }
//        print_r($sql);exit();
        //创建预处理对象
        $stmt = $this->pdo->prepare($sql);
        //执行SQL操作
        if ($stmt->execute()) {
            if ($stmt->rowCount() > 0) {
                return '成功更新了' . $stmt->rowCount() . '条数据';
            } else {
                return '没有数据被更新';
            }
        } else {
            return false;
        }
    }
    //删除操作
    public function delete($table, $where = '')
    {
        $sql = "DELETE FROM {$table} ";
        if (!empty($where)) {
            $sql .= 'WHERE ' . $where . ';';
        } else {
            die('删除必须加条件');
        }
//        print_r($sql); exit();
        $stmt = $this->pdo->prepare($sql);
        if ($stmt->execute()) {
            if ($stmt->rowCount() > 0) {
                return '成功删除了' . $stmt->rowCount() . '条数据';
            } else {
                return '找不到要删除的数据';
            }
        } else {
            return false;
        }
    }
    //查询操作
    //查询单条数据
    public function find($table, $fields, $where = '')
    {
        $sql = "SELECT ";
        if (is_array($fields)) {
            foreach ($fields as $v) {
                $sql .= $v . ',';
            }
        } else {
            $sql .= $fields;
        }
        $sql = rtrim(trim($sql), ',');
        $sql .= ' FROM ' . $table;
        if (!empty($where)) {
            $sql .= ' WHERE ' . $where;
        }
        $sql .= ' LIMIT 1;';
        $stmt = $this->pdo->prepare($sql);
        $find = $stmt->execute();
        if ($find) {
            return $stmt->fetch(PDO::FETCH_ASSOC);
        } else {
            return false;
        }
    }
    //查询多条数据
    public function select($table, $fields, $where = '', $order = '', $limit = '')
    {
        $sql = "SELECT ";
        if (is_array($fields)) {
            foreach ($fields as $field) {
                $sql .= $field . ',';
            }
        } else {
            $sql .= $fields;
        }
        $sql = rtrim(trim($sql), ',');
        $sql .= ' FROM ' . $table;
        if (!empty($where)){
            $sql .= ' WHERE '. $where;
        }
        if (!empty($order)){
            $sql .= ' ORDER BY '.$order;
        }
        if (!empty($limit)){
            $sql .= ' LIMIT '.$limit . ';';
        }
//        print_r($sql);
        $stmt = $this->pdo -> prepare($sql);
        if($stmt->execute()){
            return $stmt->fetchAll(PDO::FETCH_ASSOC);
        }
    }
    //析构函数
    public function __destruct()
    {
        $this->pdo = null;
    }
}
$db = new Db("mysql:host=localhost;dbname=movies", 'root', 'root');
//print_r($db->pdo);
//print_r($db->pdo);
//if($db->pdo){
//    echo '连接成功';
//}
//插入操作
//$insert = $db->insert('category',['name'=>'ds','alias'=>'都市生活剧']);
//echo $insert;
//更新操作
//$update = $db->update('category', ['name' => 'xj', 'alias' => '喜剧片'], '`cate_id`=23');
//echo $update;
//删除操作
//$del = $db->delete('category', '`cate_id` = 24');
//echo $del;
//查找单条记录
//$res = $db->find('category','*','cate_id = 25');
//print_r($res);
//查找多条记录
$sel = $db->select('category', '*','name="gz"','cate_id DESC','0,10');
print_r($sel);