yii2框架学习

1. 简单查询

[[one()]]: 根据查询结果返回查询的第一条记录。

[[all()]]: 根据查询结果返回所有记录。

[[count()]]: 返回记录的数量。

[[sum()]]: 返回指定列的总数。

[[average()]]: 返回指定列的平均值。

[[min()]]: 返回指定列的最小值。

[[max()]]: 返回指定列的最大值。

[[scalar()]]: 返回查询结果的第一行中的第一列的值。

[[column()]]: 返回查询结果中的第一列的值。

[[exists()]]: 返回一个值,该值指示查询结果是否有数据。

[[where()]]: 添加查询条件

[[with()]]: 该查询应执行的关系列表。

[[indexBy()]]: 根据索引的列的名称查询结果。

[[asArray()]]: 以数组的形式返回每条记录。

应用实例:

Customer::find()->one();    此方法返回一条数据;

Customer::find()->all();    此方法返回所有数据;

Customer::find()->count();    此方法返回记录的数量;

Customer::find()->average();    此方法返回指定列的平均值;

Customer::find()->min();    此方法返回指定列的最小值 ;

Customer::find()->max();    此方法返回指定列的最大值 ;

Customer::find()->scalar();    此方法返回值的第一行第一列的查询结果;

Customer::find()->column();    此方法返回查询结果中的第一列的值;

Customer::find()->exists();    此方法返回一个值指示是否包含查询结果的数据行;
Customer::find()->asArray()->one();    以数组形式返回一条数据;

Customer::find()->asArray()->all();    以数组形式返回所有数据;
Customer::find()->where($condition)->asArray()->one();    根据条件以数组形式返回一条数据;

Customer::find()->where($condition)->asArray()->all();    根据条件以数组形式返回所有数据;
Customer::find()->where($condition)->asArray()->orderBy('id DESC')->all();    根据条件以数组形式返回所有数据,并根据ID倒序;

2.关联查询

[[ActiveRecord::hasOne()]]:返回对应关系的单条记录
[[ActiveRecord::hasMany()]]:返回对应关系的多条记录

应用实例:

//客户表Model:CustomerModel
//订单表Model:OrdersModel
//国家表Model:CountrysModel
//首先要建立表与表之间的关系 
//在CustomerModel中添加与订单的关系
Class CustomerModel extends yiidbActiveRecord
{
    ...
    
    public function getOrders()
    {
        //客户和订单是一对多的关系所以用hasMany
        //此处OrdersModel在CustomerModel顶部别忘了加对应的命名空间
        //id对应的是OrdersModel的id字段,order_id对应CustomerModel的order_id字段
        return $this->hasMany(OrdersModel::className(), ['id'=>'order_id']);
    }
     
    public function getCountry()
    {
        //客户和国家是一对一的关系所以用hasOne
        return $this->hasOne(CountrysModel::className(), ['id'=>'Country_id']);
    }
    ....
}
      
// 查询客户与他们的订单和国家
CustomerModel::find()->with('orders', 'country')->all();

// 查询客户与他们的订单和订单的发货地址
CustomerModel::find()->with('orders.address')->all();

// 查询客户与他们的国家和状态为1的订单
CustomerModel::find()->with([
    'orders' => function ($query) {
        $query->andWhere('status = 1');
        },
        'country',
])->all();

注:with中的orders对应getOrders

常见问题:

在查询时加了询时加了->select();如下// 查询客户与他们的订单和国家
CustomerModel::find()->select('order_id')->with('orders', 'country')->all();
findOne()和findAllll():

// 查询key值为10的客户
$customer = Customer::findOne(10);
$customer = Customer::find()->where(['id' => 10])->one();
// 查询年龄为30,状态值为1的客户
$customer = Customer::findOne(['age' => 30, 'status' => 1]);
$customer = Customer::find()->where(['age' => 30, 'status' => 1])->one();
// 查询key值为10的所有客户
$customers = Customer::findAll(10);
$customers = Customer::find()->where(['id' => 10])->all();
// 查询key值为10,11,12的客户
$customers = Customer::findAll([10, 11, 12]);
$customers = Customer::find()->where(['id' => [10, 11, 12]])->all();
// 查询年龄为30,状态值为1的所有客户
$customers = Customer::findAll(['age' => 30, 'status' => 1]);
$customers = Customer::find()->where(['age' => 30, 'status' => 1])->all();
where()条件$customers = Customer::find()->where($cond)->all(); 

$cond写法举例// SQL: (type = 1) AND (status = 2).
$cond = ['type' => 1, 'status' => 2] 

// SQL:(id IN (1, 2, 3)) AND (status = 2)
$cond = ['id' => [1, 2, 3], 'status' => 2] 

//SQL:status IS NULL
$cond = ['status' => null]
[[and]]:将不同的条件组合在一起//SQL:`id=1 AND id=2`
$cond = ['and', 'id=1', 'id=2']

//SQL:`type=1 AND (id=1 OR id=2)`
$cond = ['and', 'type=1', ['or', 'id=1', 'id=2']]
[[or]]:

//SQL:`(type IN (7, 8, 9) OR (id IN (1, 2, 3)))`
$cond = ['or', ['type' => [7, 8, 9]], ['id' => [1, 2, 3]]
[[not]]:


//SQL:`NOT (attribute IS NULL)`
$cond = ['not', ['attribute' => null]]
[[between]]: not between 用法相同//SQL:`id BETWEEN 1 AND 10`
$cond = ['between', 'id', 1, 10]
[[in]]: not in 用法类似//SQL:`id IN (1, 2, 3)`
$cond = ['in', 'id', [1, 2, 3]]

//IN条件也适用于多字段
$cond = ['in', ['id', 'name'], [['id' => 1, 'name' => 'foo'], ['id' => 2, 'name' => 'bar']]]

//也适用于内嵌sql语句
$cond = ['in', 'user_id', (new Query())->select('id')->from('users')->where(['active' => 1])]
[[like]]:


//SQL:`name LIKE '%tester%'`
$cond = ['like', 'name', 'tester']

//SQL:`name LIKE '%test%' AND name LIKE '%sample%'`
$cond = ['like', 'name', ['test', 'sample']]

//SQL:`name LIKE '%tester'`
$cond = ['like', 'name', '%tester', false]
[[exists]]: not exists用法类似//SQL:EXISTS (SELECT "id" FROM "users" WHERE "active"=1)
$cond = ['exists', (new Query())->select('id')->from('users')->where(['active' => 1])]
此外//SQL:`id >= 10`
$cond = ['>=', 'id', 10]

//SQL:`id != 10`
$cond = ['!=', 'id', 10]

常用查询:

// WHERE admin_id >= 10 LIMIT 0,10
User::find()->select('*')->where(['>=', 'admin_id', 10])->offset(0)->limit(10)->all()
// SELECT `id`, (SELECT COUNT(*) FROM `user`) AS `count` FROM `post`   
$subQuery = (new Query())->select('COUNT(*)')->from('user');    
$query = (new Query())->select(['id', 'count' => $subQuery])->from('post');
// SELECT DISTINCT `user_id` ... 
User::find()->select('user_id')->distinct();

更新:

//update();
//runValidation boolen 是否通过validate()校验字段 默认为true 
//attributeNames array 需要更新的字段 
$model->update($runValidation , $attributeNames);  

//updateAll();
//update customer set status = 1 where status = 2
Customer::updateAll(['status' => 1], 'status = 2'); 

//update customer set status = 1 where status = 2 and uid = 1;
Customer::updateAll(['status' => 1], ['status'=> '2','uid'=>'1']);

删除:

$model = Customer::findOne($id);
$model->delete();

$model->deleteAll(['id'=>1]);

批量插入:

Yii::$app->db->createCommand()->batchInsert(UserModel::tableName(), ['user_id','username'], [
    ['1','test1'],
    ['2','test2'],
    ['3','test3'],   
])->execute();

查看执行sql

//UserModel 
$query = UserModel::find()->where(['status'=>1]); 
echo $query->createCommand()->getRawSql();
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