一、以createCommand方式：

// YII2中通过createCommand来处理数据库// 查询多条记录// {
    {%user}} 表示如果设置了表前缀，YII会自动帮你替换$data1 = YII::$app->db->createCommand('select * from {
    {%user}}')->queryAll();// 查询一条记录// createCommand的第二个参数可以进行参数绑定$data2 = YII::$app->db->createCommand('select * from {
    {%user}} where id=:id', ['id' => 2])->queryOne();// 返回一列(第一列)数据$data3 = YII::$app->db->createCommand('select name from {
    {%user}}')->queryColumn();// 返回一个标量值，常用于统计$data4 = YII::$app->db->createCommand('select count(*) as cnt from {
    {%user}}')->queryScalar();// 绑定参数，防止SQL注入问题// bindValue绑定一个参数$data5 = YII::$app->db->createCommand('select * from {
    {%user}} where id=:id')    ->bindValue(':id', 3)    ->queryOne();// 绑定多个参数$data6 = YII::$app->db->createCommand('select * from {
    {%user}} where id=:id and name=:name')    ->bindValues([':id' => 5, ':name' => 'eee'])    ->queryOne();// 绑定参数引用$id = 7;$data7 = YII::$app->db->createCommand('select * from {
    {%user}} where id=:id')    ->bindParam(':id', $id)    ->queryOne();// 执行非查询语句$data8 = YII::$app->db->createCommand('update {
    {%user}} set name=:name where id=:id')    ->bindValues([':name' => 'abcdef', ':id' => 8])    ->execute();// 当然，我们也可以用更加简便的方法// insert()插入$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::$app->db->createCommand()->update('{
    {%user}}', [    'name' => '1242143214'], 'id=:id', ['id' => 10])->execute();// delete()删除$data12 = YII::$app->db->createCommand()->delete('{
    {%user}}', 'id=:id', ['id' => 11])->execute();// 执行事务$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) {    //如果语句中有一个执行失败，那么就将回滚    $trans->rollBack();    throw $e;}// 获取表的定义信息$info = YII::$app->db->getTableSchema('{
    {%user}}');

　　

二、以AR(Active Record)方式操作数据库

我们需要创建一个继承自\yii\db\ActiveRecord的模型，然后重写tableName()函数，返回要操作的表名。

常用操作如下：

// 查询一条记录// asArray的作用是以数组形式返回结果// find()会返回一个ActiveQuery对象，ActiveQuery对象继承自yii\db\Query，所以可以使用Query中的所有查询方法$data1 = MyUser::find()->where(['id' => 1])->asArray()->one();// 查询多条记录$data2 = MyUser::find()->where([])->orderBy('id desc')->asArray()->all();// 根据主键获取一条记录$data3 = MyUser::findOne(3);// 根据主键获取多条记录$data4 = MyUser::findAll([4, 5, 6, 7]);// 带条件查询多条记录$data5 = MyUser::findAll(['sex' => 1]);// 运行原生SQL$data6 = MyUser::findBySql('select * from {
    {%user}} where id=:id', [':id' => 8])->asArray()->one();// 添加数据// 准备一个新的实例，然后设置对应字段属性，保存$user = new MyUser();$user->name = 'test';$user->sex = 1;$user->age = 22;$user->save();// 修改数据// 先获取一个对象，然后设置对应字段属性，保存$upd = MyUser::findOne(10);$upd->name = 'abcdefg';$upd->save();// 修改多条数据$data7 = MyUser::updateAll(['name' => 'update'], ['sex' => 1]);// 删除一条数据$del = MyUser::findOne(15);$del->delete();// 删除多条数据$data8 = MyUser::deleteAll(['sex' => 0]);// 事务操作$user2 = MyUser::findOne(22);$user3 = MyUser::findOne(33);$trans = MyUser::getDb()->beginTransaction();try {    $user2->name = '2222';    $user3->name = '3333';    //修改数据    $user2->save();    $user3->save();    $trans->commit();} catch (\Exception $e) {    $trans->rollBack();    throw $e;}

具体更多的操作方式建议查看官方文档。