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 '%aa%') OR (`name` LIKE '%bb%'))
$data15 = (new Query())- select(['id', 'name'])
- from('{{%user}}')
- where([
'and',
['sex' =  1],
[
'or',
['like', 'name', 'aa'],
['like', 'name', 'bb'],
],
])
- all();
//有些时候我们需要根据用户传递过来的参数追加where条件
//追加and条件
$query = (new Query())- select(['id', 'name'])
- from('{{%user}}')
- where('sex=1');
//追加age大于18的条件
$query- andWhere([' ', 'age', 18]);
echo $query- createCommand()- getRawSql();
//追加or条件
$query2 = (new Query())- select(['id', 'name'])
- from('{{%user}}')
- where(['like', 'name', 'aa']);
//追加name相似bb的条件
$query2- orWhere(['like', 'name', 'bb']);
echo $query2- createCommand()- getRawSql();
//表别名和连接查询
//SELECT `u`.`id`, `u`.`name`, `aa`.`item_name` FROM `tb_user` `u` LEFT JOIN `tb_auth_assignment` `aa` ON aa.user_id = u.id
$data16 = (new Query())- select(['u.id', 'u.name', 'aa.item_name'])
- from(['u' =  '{{%user}}'])
- leftJoin(['aa' =  '{{%auth_assignment}}'], 'aa.user_id = u.id')
- all();
}
}