// YII2中通過createCommand來處理數據庫
 
// 查詢多條記錄
// {{%user}} 表示如果設置了表前綴，YII會自動幫你替換
$data1 = YII::$app->db->createCommand('select * from {{%user}}')->queryAll();
 
 
// 查詢一條記錄
// createCommand的第二個參數可以進行參數綁定
$data2 = YII::$app->db->createCommand('select * from {{%user}} where id=:id', ['id' => 2])->queryOne();
 
 
// 返回一列(第一列)數據
$data3 = YII::$app->db->createCommand('select name from {{%user}}')->queryColumn();
 
 
// 返回一個標量值，常用于統計
$data4 = YII::$app->db->createCommand('select count(*) as cnt from {{%user}}')->queryScalar();
 
// 綁定參數，防止SQL注入問題
// bindValue綁定一個參數
$data5 = YII::$app->db->createCommand('select * from {{%user}} where id=:id')
  ->bindValue(':id', 3)
  ->queryOne();
 
// 綁定多個參數
$data6 = YII::$app->db->createCommand('select * from {{%user}} where id=:id and name=:name')
  ->bindValues([':id' => 5, ':name' => 'eee'])
  ->queryOne();
 
// 綁定參數引用
$id = 7;
$data7 = YII::$app->db->createCommand('select * from {{%user}} where id=:id')
  ->bindParam(':id', $id)
  ->queryOne();
 
// 執行非查詢語句
$data8 = YII::$app->db->createCommand('update {{%user}} set name=:name where id=:id')
  ->bindValues([':name' => 'abcdef', ':id' => 8])
  ->execute();
 
// 當然，我們也可以用更加簡便的方法
// insert()插入
$data9 = YII::$app->db->createCommand()->insert('{{%user}}', [
  'name' => 'test',
  'sex' => 1,
  'age' => 28,
])->execute();
 
// batchInsert()批量插入
$data10 = YII::$app->db->createCommand()->batchInsert('{{%user}}', ['name', 'sex', 'age'], [
  ['111', 1, 11],
  ['222', 1, 22],
])->execute();
 
// update()更新
$data11 = YII::$app->db->createCommand()->update('{{%user}}', [
  'name' => '1242143214'
], 'id=:id', ['id' => 10])->execute();
 
// delete()刪除
$data12 = YII::$app->db->createCommand()->delete('{{%user}}', 'id=:id', ['id' => 11])->execute();
 
 
// 執行事務
$trans = YII::$app->db->beginTransaction();
 
try {
  YII::$app->db->createCommand()->update('{{%user}}', ['age' => 12], 'id=:id', ['id' => 13])->execute();
  YII::$app->db->createCommand()->update('{{%user}}', ['age' => 22], 'id=:id', ['id' => 14])->execute();
 
  $trans->commit();
} catch (\Exception $e) {
  //如果語句中有一個執行失敗，那么就將回滾
  $trans->rollBack();
  throw $e;
}
 
// 獲取表的定義信息
$info = YII::$app->db->getTableSchema('{{%user}}');

?php
namespace app\models;
 
use yii\db\ActiveRecord;
 
class MyUser extends ActiveRecord
{
  public static function tableName()
  {
    return '{{%user}}';
  }
}

// 查詢一條記錄
// asArray的作用是以數組形式返回結果
// find()會返回一個ActiveQuery對象，ActiveQuery對象繼承自yii\db\Query，所以可以使用Query中的所有查詢方法
$data1 = MyUser::find()->where(['id' => 1])->asArray()->one();
 
// 查詢多條記錄
$data2 = MyUser::find()->where([])->orderBy('id desc')->asArray()->all();
 
// 根據主鍵獲取一條記錄
$data3 = MyUser::findOne(3);
 
// 根據主鍵獲取多條記錄
$data4 = MyUser::findAll([4, 5, 6, 7]);
 
// 帶條件查詢多條記錄
$data5 = MyUser::findAll(['sex' => 1]);
 
// 運行原生SQL
$data6 = MyUser::findBySql('select * from {{%user}} where id=:id', [':id' => 8])->asArray()->one();
 
// 添加數據
// 準備一個新的實例，然后設置對應字段屬性，保存
$user = new MyUser();
$user->name = 'test';
$user->sex = 1;
$user->age = 22;
$user->save();
 
// 修改數據
// 先獲取一個對象，然后設置對應字段屬性，保存
$upd = MyUser::findOne(10);
$upd->name = 'abcdefg';
$upd->save();
 
// 修改多條數據
$data7 = MyUser::updateAll(['name' => 'update'], ['sex' => 1]);
 
// 刪除一條數據
$del = MyUser::findOne(15);
$del->delete();
 
// 刪除多條數據
$data8 = MyUser::deleteAll(['sex' => 0]);
 
// 事務操作
$user2 = MyUser::findOne(22);
$user3 = MyUser::findOne(33);
$trans = MyUser::getDb()->beginTransaction();
try {
  $user2->name = '2222';
  $user3->name = '3333';
  //修改數據
  $user2->save();
  $user3->save();
 
  $trans->commit();
} catch (\Exception $e) {
  $trans->rollBack();
  throw $e;
}