Yii2.0数据库操作增删改查详解（转）

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

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

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

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

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

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

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

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

9. 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；

10. Customer::find()->asArray()->one();    以数组形式返回一条数据；

11. Customer::find()->asArray()->all();    以数组形式返回所有数据；

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

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

14. 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；
    

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1212

findOne()和findAll():

// 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，用法举例：

//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，您可以指定任意运算符如下

//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();123456789123456789

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 = 2Customer::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();