YetiForceCompany/YetiForceCRM

<?php
/**
 * @copyright YetiForce S.A.
 * @license   YetiForce Public License 6.5 (licenses/LicenseEN.txt or yetiforce.com)
 * @author    Mariusz Krzaczkowski <m.krzaczkowski@yetiforce.com>
 */

namespace App\Db;

/**
 * Query represents a SELECT SQL statement in a way that is independent of DBMS.
 *
 * Query provides a set of methods to facilitate the specification of different clauses
 * in a SELECT statement. These methods can be chained together.
 *
 * By calling [[createCommand()]], we can get a [[Command]] instance which can be further
 * used to perform/execute the DB query against a database.
 */
class Query extends \yii\db\Query
{
    /**
     * Creates a DB command that can be used to execute this query.
     *
     * @param \App\Db $db the database connection used to generate the SQL statement.
     *                    If this parameter is not given, the `db` application component will be used.
     *
     * @return Command the created DB command instance.
     */
    public function createCommand($db = null)
    {
        if (null === $db) {
            $db = \App\Db::getInstance();
        }
        [$sql, $params] = $db->getQueryBuilder()->build($this);

        return $db->createCommand($sql, $params);
    }

    /**
     * Starts a batch query.
     *
     * A batch query supports fetching data in batches, which can keep the memory usage under a limit.
     * This method will return a [[BatchQueryResult]] object which implements the [[\Iterator]] interface
     * and can be traversed to retrieve the data in batches.
     *
     * @param int     $batchSize the number of records to be fetched in each batch.
     * @param \App\Db $db        the database connection. If not set, the "db" application component will be used.
     *
     * @return \yii\db\BatchQueryResult the batch query result. It implements the [[\Iterator]] interface
     *                                  and can be traversed to retrieve the data in batches.
     */
    public function batch($batchSize = 100, $db = null)
    {
        if (null === $db) {
            $db = \App\Db::getInstance();
        }
        return \Yii::createObject([
            'class' => \yii\db\BatchQueryResult::className(),
            'query' => $this,
            'batchSize' => $batchSize,
            'db' => $db,
            'each' => false,
        ]);
    }

    /**
     * Starts a batch query and retrieves data row by row.
     *
     * This method is similar to [[batch()]] except that in each iteration of the result,
     * only one row of data is returned. For example,
     *
     * @param int     $batchSize the number of records to be fetched in each batch.
     * @param \App\Db $db        the database connection. If not set, the "db" application component will be used.
     *
     * @return \yii\db\BatchQueryResult the batch query result. It implements the [[\Iterator]] interface
     *                                  and can be traversed to retrieve the data in batches.
     */
    public function each($batchSize = 100, $db = null)
    {
        if (null === $db) {
            $db = \App\Db::getInstance();
        }
        return \Yii::createObject([
            'class' => \yii\db\BatchQueryResult::class,
            'query' => $this,
            'batchSize' => $batchSize,
            'db' => $db,
            'each' => true,
        ]);
    }

    /**
     * Executes the query and returns a single row of result.
     *
     * @param \App\Db $db the database connection used to generate the SQL statement.
     *                    If this parameter is not given, the `db` application component will be used.
     *
     * @return array|bool the first row (in terms of an array) of the query result. False is returned if the query
     *                    results in nothing.
     */
    public function one($db = null)
    {
        return $this->limit(1)->createCommand($db)->queryOne();
    }

    /**
     * Returns the query result as a scalar value.
     * The value returned will be the first column in the first row of the query results.
     *
     * @param \App\Db $db the database connection used to generate the SQL statement.
     *                    If this parameter is not given, the `db` application component will be used.
     *
     * @return string|false|null the value of the first column in the first row of the query result.
     *                           False is returned if the query result is empty.
     */
    public function scalar($db = null)
    {
        return $this->limit(1)->createCommand($db)->queryScalar();
    }

    /**
     * Queries a scalar value by setting [[select]] first.
     * Restores the value of select to make this query reusable.
     *
     * @param string|ExpressionInterface $selectExpression
     * @param \App\Db|null               $db
     *
     * @return bool|string
     */
    protected function queryScalar($selectExpression, $db)
    {
        if (!$this->distinct
        && empty($this->groupBy)
        && empty($this->having)
        && empty($this->union)) {
            return parent::queryScalar($selectExpression, $db);
        }
        $command = (new static())
            ->select([$selectExpression])
            ->from(['c' => $this])
            ->createCommand($db);
        $this->setCommandCache($command);
        return $command->queryScalar();
    }
}