php - 使用 Yii Active Record 查找最多一列

Question

Yii Active Record如何找到数据库中一列的最大值？

我可以通过纯 sql 和createCommand方法来完成，但我想通过 Active Record 和CDbCriteria类来完成。有什么办法吗？

Answer 1

您需要按如下方式更改选择标准。

$model = new Model;
$criteria=new CDbCriteria;
$criteria->select='max(column) AS maxColumn';
$row = $model->model()->find($criteria);
$somevariable = $row['maxColumn'];

参考：

http://www.yiiframework.com/forum/index.php/topic/6730-how-can-i-use-max-in-find-method/page_view_findpost_p_80659 _ _ _ _

Answer 2

这避免了创建不必要的临时对象：

$criteria = new CDbCriteria;
$criteria->select = 'max(column)';
// additional where conditions, if you so wish
$criteria->addColumnCondition(array('published' => 1));
$model = SomeModel::model();
$value = $model->commandBuilder->createFindCommand(
    $model->tableName(), $criteria)->queryScalar();

Answer 3

您可以通过 DESC 限制结果和顺序，例如

$criteria = new CDbCriteria;
$criteria->order = 'column DESC';
$row = Model::model()->find($criteria);
$somevariable = $row->column;

Answer 4

如果您需要 WHERE 子句：

在控制器中：

$max = $model->getMax($filter);

在模型中：

public $maxColumn = 0;
public function getMax($filter = null)
{
    /* Get max in column1 WHERE column2 = $filter */
    $criteria               = new CDbCriteria;
    $criteria->select       = 'MAX(t.column1) as maxColumn';
    $criteria->condition    = 't.column2 LIKE :parm';
    $criteria->params       = array(':parm'=>$filter);

    $tempmodel  = $this->find($criteria);
    $max        = $tempmodel['maxColumn'];
    return $max;
}

Answer 5

$model = MyModel::model();

$maxId = $model->getCommandBuilder()
        ->createSqlCommand('SELECT MAX(id) FROM '.$model->tableName())
        ->queryScalar();

$maxId = Yii::app()->db
        ->createCommand('SELECT MAX(id) FROM '.$model->tableName())
        ->queryScalar();

Answer 6

就是这个。

function getMaxId( $modelName ){
    $criteria = new CDbCriteria;
    $criteria->order = 'id DESC';
    $model = $modelName::model()->find( $criteria );
    return $model->id;
}