php Yii2：检查数据库中存在的 ActiveRecord 模型
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Yii2: check exist ActiveRecord model in database
提问by Hett
How to check existence of model in DB?
In Yii 1 version it was so
User::model()->exist()
如何检查数据库中模型的存在？在 Yii 1 版本中是这样
User::model()->exist()
回答by ippi
In Yii2 you can add exists()to your query chain:
在 Yii2 中，您可以添加exists()到查询链中：
User::find()
->where( [ 'id' => 1 ] )
->exists();
(The generated SQL looks like this: SELECT 1 FROM `tbl_user` WHERE `id`=1.)
（生成的 SQL 如下所示：SELECT 1 FROM `tbl_user` WHERE `id`=1.）
Here is Query->exists()from Yii2 source:
这是Query->exists()来自 Yii2 的源代码：
/**
* Returns a value indicating whether the query result contains any row of data.
* @param Connection $db the database connection used to generate the SQL statement.
* If this parameter is not given, the `db` application component will be used.
* @return bool whether the query result contains any row of data.
*/
public function exists($db = null)
{
if ($this->emulateExecution) {
return false;
}
$command = $this->createCommand($db);
$params = $command->params;
$command->setSql($command->db->getQueryBuilder()->selectExists($command->getSql()));
$command->bindValues($params);
return (bool) $command->queryScalar();
}
回答by Shaneesh P
if(Mastersettings::find()->where(['id'=>1,'status'=>1])->exists())
{
//....... Your code Here ......
}
http://yii2ideas.blogspot.in/2017/06/yii2-database-operations.html
http://yii2ideas.blogspot.in/2017/06/yii2-database-operations.html
