Yii2框架操作数据库的方法分析【以mysql为例】

DROP TABLE IF EXISTS `pre_user`;
CREATE TABLE `pre_user`(
  `id` int(11) AUTO_INCREMENT PRIMARY KEY,
  `username` varchar(255) NOT NULL,
  `password` varchar(32) NOT NULL DEFAULT '',
  `password_hash` varchar(255) NOT NULL DEFAULT '',
  `email` varchar(255) NOT NULL DEFAULT '',
  `status` smallint(6) NOT NULL DEFAULT 10,
  `created_at` smallint(6) NOT NULL DEFAULT 0,
  `updated_at` smallint(6) NOT NULL DEFAULT 0
)ENGINE=InnoDB DEFAULT CHARSET=utf8mb4;

<?php
return [
  'class' => 'yii\db\Connection',
  'dsn' => 'mysql:host=localhost;dbname=yii2',
  'username' => 'root',
  'password' => 'root',
  'charset' => 'utf8mb4',
  'tablePrefix' => 'pre_'
];

var_dump(\Yii::$app->db);

// 接收表单的数据
$username = 'jack';
$sql = "INSERT INTO {{%user}} (username,status) VALUES (:username,:status)";
// 返回受影响行数
$row = \Yii::$app->db->createCommand($sql,['username'=>$username,'status'=>8])->execute();
// 获取自增ID
echo \Yii::$app->db->getLastInsertID();

$sql = "SELECT  FROM {{%user}} WHERE id>:id";
// 查询结果是一个二维数组
$userArr = \Yii::$app->db->createCommand($sql,['id'=>1])->queryAll();
// 如果要查询一个
$user = \Yii::$app->db->createCommand($sql,['id'=>1])->queryOne();
// 如果要返回单值
// 例如 select count()语句
$count = \Yii::$app->db->createCommand($sql,['id'=>1])->queryScalar();
echo $count;