YII2框架中查询生成器Query()的使用方法示例

<?php
namespace app\controllers;
 
use YII;
use yii\db\Query;
use yii\web\Controller;
 
class TestController extends Controller
{
  public function actionTest()
  {
    //YII2的Query的使用
    //Query与createCommand的区别是createCommand是直接写一个SQL来执行。
    //Query是根据参数和数据库类型生成不同的SQL，提升数据库可迁移性。
 
    //通过all查询多条记录
    //我这里用tb_user表来进行演示
    $data1 = (new Query())->select(['id', 'name'])
      ->from('{{%user}}')
      ->all();
 
    //指定where条件查询
    $data2 = (new Query())->select(['id', 'name'])
      ->from('{{%user}}')
      ->where('id=:id', [':id' => '2'])
      ->all();
 
    //通过one查询单条记录
    $data3 = (new Query())->select(['id', 'name'])
      ->from('{{%user}}')
      ->where('id=3')
      ->one();
 
    //判断记录是否存在
    $exists = (new Query())->from('{{%user}}')
      ->where('name="aaa"')
      ->exists();
 
    if ($exists) {
      echo 'name=aaa 存在';
    }
 
    //定义字段别名
    //注意真实的字段名写后面，别名写前面
    $data4 = (new Query())->select(['ids' => 'id', 'names' => 'name'])
      ->from('{{%user}}')
      ->where('1=1')
      ->all();
 
    //通过orderby排序，和limit限制条数
    $data5 = (new Query())->select(['id', 'name'])
      ->from('{{%user}}')
      ->where('1=1')
      ->orderBy('id desc')
      ->limit(3)
      ->all();
 
    //多个and条件
    //参数是数组，一个key对应一个value，默认以and拼接
    $data6 = (new Query())->select(['id', 'name'])
      ->from('{{%user}}')
      ->where(['id' => 3, 'name' => 'aaa'])
      ->one();
 
    //in条件
    $data7 = (new Query())->select(['id', 'name'])
      ->from('{{%user}}')
      ->where(['id' => [4, 5, 6]])
      ->all();
 
    //或者如下方式
    $data7_2 = (new Query())->select(['id', 'name'])
      ->from('{{%user}}')
      ->where(['in', 'id', [4, 5, 6]])
      ->all();
 
    //count统计
    $count = (new Query())->from('{{%user}}')->count();
    echo '总记录数: ', $count;
 
    //大于，大于等于，小于，小于等于where条件
    $data8 = (new Query())->select(['id', 'name'])
      ->from('{{%user}}')
      ->where(['>=', 'id', 5])
      ->all();
 
    $data9 = (new Query())->select(['id', 'name'])
      ->from('{{%user}}')
      ->where(['<=', 'id', 3])
      ->all();
 
    //like查询
    $data10 = (new Query())->select(['id', 'name'])
      ->from('{{%user}}')
      ->where(['like', 'name', 'dd'])
      ->all();
 
    //between筛选和group by分组
    //查找出age在18到24之间的，并按sex分组
    $data11 = (new Query())->select(['id', 'name'])
      ->from('{{%user}}')
      ->where(['between', 'age', 18, 24])
      ->groupBy('sex')
      ->all();
 
    //having筛选
    //按sex分组，然后统计人数大于3的
    $data12 = (new Query())->select(['sex', 'cnt' => 'count(*)'])
      ->from('{{%user}}')
      ->groupBy('sex')
      ->having('cnt > 3')
      ->all();
 
    //or逻辑条件
    //查找姓名为aaa或bbb的用户
    //之前where数组是以key=>value方式传递的，如果要表达复杂逻辑关系，
    //数组第一个元素必须声明是什么逻辑，and还是or
    //第二个元素表示逻辑左边
    //第三个元素表示逻辑右边
    $data13 = (new Query())->select(['id', 'name'])
      ->from('{{%user}}')
      ->where(['or', ['name' => 'aaa'], ['name' => 'bbb']])
      ->all();
 
    //复杂的where条件
    //我这里只是作为演示
    //SELECT `id`, `name` FROM `tb_user` WHERE ((`name`='aaa') OR (`name`='bbb')) OR ((`name`='ccc') OR (`name`='ddd'))
    $data14 = (new Query())->select(['id', 'name'])
      ->from('{{%user}}')
      ->where([
        'or',
        [
          'or',
          ['name' => 'aaa'],
          ['name' => 'bbb'],
        ],
        [
          'or',
          ['name' => 'ccc'],
          ['name' => 'ddd'],
        ],
      ])
      ->all();
 
    //and和or嵌套where条件
    //SELECT `id`, `name` FROM `tb_user` WHERE (`sex`=1) AND ((`name` LIKE '