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我有两个模型，列表和预订。列表有很多预订。我正在尝试编写一个查询以返回在特定时间段内没有预订的所有列表。

我到目前为止，但我仍然是 cakephp 的新手，我的 sql 也不是很好。在我的控制器方法中，我有

$conditions = array(
                            "OR" => array(
                                "Listing.address_one LIKE" => "%".$area."%",
                                "Listing.address_two LIKE" => "%".$area."%",
                                "Listing.city LIKE" => "%".$area."%",
                                "Listing.postcode LIKE" => "%".$area."%",
                                "Listing.title LIKE" => "%".$area."%",
                            )

                        );


    $this->paginate = array(
                'conditions'=> $conditions,
                'joins'=>array(
                          array(
                           'table'=>'bookings',
                           'alias'=>'Booking',
                           'type' =>'inner',
                           'conditions' =>array('Booking.listing_id = Listing.id', 'Booking.checkin NOT BETWEEN ? AND ?' => array($to, $from))
                          )
                        ),
                'limit' => 10,
                );

    $data = $this->paginate();

这只会获取所有实际具有与之关联的预订的列表。不仅如此，它还不会忽略在给定时间段内预订的任何预订。

它创建的 SQL 是：

SELECT 
    ...
FROM 
    `database`.`listings` AS `Listing` 
INNER JOIN 
    `database`.`bookings` AS `Booking` ON (
        `Booking`.`listing_id` = `Listing`.`id` AND
        `Booking`.`checkin` NOT BETWEEN '18-07-2013' AND '10-07-2013'
     ) 
LEFT JOIN 
    `database`.`users` AS `User` ON (
        `Listing`.`user_id` = `User`.`id`
     ) 
WHERE (
    (`Listing`.`address_one` LIKE '%belfast%') OR 
    (`Listing`.`address_two` LIKE '%belfast%') OR 
    (`Listing`.`city` LIKE '%belfast%') OR 
    (`Listing`.`postcode` LIKE '%belfast%') OR 
    (`Listing`.`title` LIKE '%belfast%')
)
LIMIT 10

这看起来有点正确（？）但显然不是。有人有什么想法吗？谢谢

4

1 回答 1

1

返回在特定时间段内没有预订的所有房源

生成适当查找的第一步是了解所需的查询类型 - 即从数据库开始。

问题中的查询正在查找预订日期范围之外的所有列表（匹配条件）。即在任何时间预订贝尔法斯特除外BETWEEN '18-07-2013' AND '10-07-2013'。这和上面那句话的逻辑不一样。

有多种方法可以实现这一点，为了便于实施，这里有两种方法：

使用左连接

SELECT 
    *
FROM 
    `nights2stay`.`listings` AS `Listing` 
LEFT JOIN                                                             # <-
    `nights2stay`.`bookings` AS `Booking` ON (
        `Booking`.`listing_id` = `Listing`.`id` AND
        `Booking`.`checkin` BETWEEN '18-07-2013' AND '10-07-2013'     # <-
     ) 
LEFT JOIN 
    `nights2stay`.`users` AS `User` ON (
        `Listing`.`user_id` = `User`.`id`
     ) 
WHERE 
    (
        (`Listing`.`address_one` LIKE '%belfast%') OR 
        (`Listing`.`address_two` LIKE '%belfast%') OR 
        (`Listing`.`city` LIKE '%belfast%') OR 
        (`Listing`.`postcode` LIKE '%belfast%') OR 
        (`Listing`.`title` LIKE '%belfast%')
    ) AND
    `Booking`.`id` IS NULL                                            # <-
LIMIT 10

即加入与日期范围匹配的日期的预订，并且只返回没有预订的记录。

实现上面的查询很容易：

function index() {
    ... # Existing code

    $this->paginate['joins'][0]['type'] = 'LEFT';
    $this->paginate['conditions']['Booking.id'] = null;
    $data = $this->paginate();

    $this->set('data', $data);
}

使用不存在

或者，使用NOT EXISTS：

SELECT 
    *
FROM 
    `nights2stay`.`listings` AS `Listing`
                                                                      # <
LEFT JOIN 
    `nights2stay`.`users` AS `User` ON (
        `Listing`.`user_id` = `User`.`id`
     ) 
WHERE 
    (
        (`Listing`.`address_one` LIKE '%belfast%') OR 
        (`Listing`.`address_two` LIKE '%belfast%') OR 
        (`Listing`.`city` LIKE '%belfast%') OR 
        (`Listing`.`postcode` LIKE '%belfast%') OR 
        (`Listing`.`title` LIKE '%belfast%')
    ) AND
    NOT EXISTS (                                                      # <
        SELECT                                                        # <
            *                                                         # <
        FROM                                                          # <
            `nights2stay`.`bookings` AS `Booking`                     # <
        WHERE                                                         # <
            `Booking`.`listing_id` = `Listing`.`id` AND               # <
            `Booking`.`checkin` BETWEEN '18-07-2013' AND '10-07-2013' # <
    )                                                                 # <
LIMIT 10

这种查询更合乎逻辑，并且它的好处是它是一个有意义的查询“在没有的地方找到我这些 (...)”。它可能会表现得更好，尽管与任何查询一样，最好在选择一个或另一个之前对查询进行分析/解释。

要实现上面的查询，在 CakePHP 中涉及更多一点，但并不难：

function index() {
    ... 

    $db = $this->Listing->getDatasource();
    $subQuery = $db->buildStatement(array(
        'fields'     => "*",
        'table'      => $db->fullTableName('bookings'),
        'alias'      => 'Booking'
        'conditions' => array(
            '`Booking`.`listing_id` = `Listing`.`id`',
            "`Booking`.`checkin` BETWEEN '$to' AND '$from'"
        )
    ));

    $expression = $db->expression('NOT EXISTS (' . $subQuery . ')');

    $this->paginate['conditions'][] = $expression;
    $data = $this->paginate();

    $this->set('data', $data);
}
于 2013-07-09T08:55:05.633 回答