更改查询sql

Question

我有以下查询来获取一年中 52 周的数据的平均值如下：

$dates = array();
$firstDate = date("Y-m-d", strtotime('first day of January 2016'));
$lastDate  = date("Y-m-d", strtotime('last day of December 2016'));

for($i=strtotime($firstDate); $i<=strtotime($lastDate); $i+=86400 *7){
  array_push($dates, date("Y-m-d", strtotime('monday this week', $i)));
}

for($i = 0; $i < count($dates); $i++){

  $sql = "SELECT pr_products.product,
  CONCAT(YEAR('".$dates[$i]."'),'-',LPAD(WEEK('".$dates[$i]."'),2,'0')) AS Week,
  SUM(IF(sw_sowing.type = 'SW', sw_sowing.quantity,0)) AS PlantSowing,
  SUM(IF(ROUND(DATEDIFF(TIMESTAMPADD(DAY,(6      WEEKDAY('".$dates[$i]."')),'".$dates[$i]."'), sw_sowing.date)/7) >= pr_products.week_production AND sw_sowing.type = 'SW',sw_sowing.quantity,0)) AS              production
FROM (
      SELECT max(sw_sowing.id) AS id
      FROM sw_sowing
      WHERE sw_sowing.status != 0
      AND sw_sowing.id_tenant = :id_tenant
      AND sw_sowing.status = 100
      AND sw_sowing.date <= TIMESTAMPADD(DAY,(6-WEEKDAY('".$dates[$i]."')),'".$dates[$i]."')
     GROUP BY sw_sowing.id_production_unit_detail
     ) AS sw
     INNER JOIN sw_sowing ON sw_sowing.id = sw.id
     INNER JOIN pr_products ON pr_products.id = sw_sowing.id_product
     INNER JOIN pr_varieties ON sw_sowing.id_variety = pr_varieties.id
     INNER JOIN pr_lands ON pr_lands.id = sw_sowing.id_land
     WHERE pr_varieties.code != 1
     AND sw_sowing.id_product = 1
     AND sw_sowing.status = 100
     GROUP BY pr_products.product
     HAVING plantSowing > 0
     ORDER BY pr_products.product";

}

我最初声明了两个变量，$firstdate 是开始日期，$lastDate 是结束日期。

然后我做一个 for 遍历这两个日期，并将每周星期一的日期保存在一个数组中。

然后我遍历那个新数组以每周获取我需要的数据。

注意：在查询中，变量 $dates[$i] 是每周的星期一日期。

无论如何，该查询运行良好，因为它为我提供了一年中 52 周所需的数据。问题是这需要一段时间。

我已经在mysql中索引了表，我改进了一点但还不够，查询实际上并不重，平均每个周期需要0.60秒。

我想知道是否有可能删除我正在做的事情并在查询中添加我不知道的WHERE，它比较两个日期并为我带来数据，或者是否有任何改进查询的方法。

我已经用答案的建议更新了查询：

$data  = array();

$start = new DateTime('first monday of January 2016');
$end   = new DateTime('last day of December 2016');

$datePeriod = new DatePeriod($start , new DateInterval('P7D') , $end);

$sql = "SELECT product AS product,
            Week AS label,
            ROUND(SUM(harvest)/SUM(production),2) AS value
            FROM (
                    (
                        SELECT pr_products.product,
                               CONCAT(YEAR(:dates),'-', LPAD(WEEK(:dates1),2,'0')) AS Week,
                               SUM(IF(sw_sowing.type = 'SW', sw_sowing.quantity,0)) AS PlantSowing,
                               SUM(IF(ROUND(DATEDIFF(TIMESTAMPADD(DAY,(6-WEEKDAY(:dates2)),:dates3), sw_sowing.date)/7) >= pr_products.week_production AND sw_sowing.type = 'SW',sw_sowing.quantity,0)) AS production,
                               0 AS Harvest
                        FROM (
                                SELECT max(sw_sowing.id) AS id
                                FROM sw_sowing
                                WHERE sw_sowing.status != 0
                                AND sw_sowing.date <= TIMESTAMPADD(DAY,(6-WEEKDAY(:dates4)),:dates5)
                                GROUP BY sw_sowing.id_production_unit_detail
                             ) AS sw
                        INNER JOIN sw_sowing ON sw_sowing.id = sw.id
                        INNER JOIN pr_products ON pr_products.id = sw_sowing.id_product
                        INNER JOIN pr_varieties ON sw_sowing.id_variety = pr_varieties.id
                        WHERE pr_varieties.code != 1
                        AND sw_sowing.id_product = 1
                        AND sw_sowing.status = 100
                        AND sw_sowing.id_tenant = :id_tenant
                        GROUP BY pr_products.product
                        HAVING plantSowing > 0
                        ORDER BY pr_products.product
                    )
                    UNION ALL
                    (
                        SELECT  pr_products.product,
                                CONCAT(YEAR(:dates6),'-', LPAD(WEEK(:dates7),2,'0')) AS Week,
                                0 AS plantSowing,
                                0 AS Production,
                                SUM(pf_harvest.quantity) AS Harvest
                        FROM pf_harvest
                        INNER JOIN pr_products ON pr_products.id = pf_harvest.id_product
                        INNER JOIN pr_varieties ON pr_varieties.id = pf_harvest.id_variety
                        INNER JOIN pf_performance ON pf_performance.id = pf_harvest.id_performance
                        WHERE pf_harvest.date BETWEEN TIMESTAMPADD(DAY,(0-WEEKDAY(:dates8)),:dates9)
                        AND TIMESTAMPADD(DAY,(6-WEEKDAY(:dates10)),:dates11)
                        AND pr_varieties.code != 1
                        AND pf_harvest.id_product = 1
                        AND pf_performance.status = 100
                        AND pf_harvest.id_tenant = :id_tenant1
                        GROUP BY pr_products.product
                        ORDER BY pr_products.product
                        )
                    ) AS sc
            GROUP BY product, label
            ORDER BY label";

       $statement = $this->db->prepare($sql);
       $id_tenant = $this->getIdTenant();

       foreach($datePeriod AS $dates){

         $values = [
           ':dates'      => $dates->format('Y-m-d'),
           ':dates1'     => $dates->format('Y-m-d'),
           ':dates2'     => $dates->format('Y-m-d'),
           ':dates3'     => $dates->format('Y-m-d'),
           ':dates4'     => $dates->format('Y-m-d'),
           ':dates5'     => $dates->format('Y-m-d'),
           ':dates6'     => $dates->format('Y-m-d'),
           ':dates7'     => $dates->format('Y-m-d'),
           ':dates8'     => $dates->format('Y-m-d'),
           ':dates9'     => $dates->format('Y-m-d'),
           ':dates10'    => $dates->format('Y-m-d'),
           ':dates11'    => $dates->format('Y-m-d'),
           ':id_tenant'  => $id_tenant,
           ':id_tenant1' => $id_tenant
         ];

         $result = $this->db->executePrepared($statement , $values);
         $data[] = $result->fetchAll();
      }

$this -> jsonReturnSuccess($data);

Answer 1

您必须考虑到您的整个代码都需要改进。首先，利用 PHP 的资源来做一些改进。

日期期间

创建一年中的第一个和最后一个星期一之间的时间段。使用DatePeriod：

$start = new \DateTime('first monday of this year');
$end = new \DateTime('first day of next year');//The last date is never reached, so if the year ends in a monday, you won't have any problem
$datePeriod = new \DatePeriod($start , new \DateInterval('P7D') , $end);

foreach($datePeriod as $date)
{
    echo $period->format('Y-m-d');
}

与您的 for 循环相比，它非常快。

array_push

注意：如果您使用 array_push() 向数组添加一个元素，最好使用 $array[] = 因为这样就没有调用函数的开销。

如手册所说，如果要向数组中添加元素，请使用 $array[]。

准备好的声明

我发现的其他常见问题，请使用prepared statement。它可用于让您的查询获得“预编译”状态（简单示例）：

$query = 'SELECT * FROM table WHERE id = :id';
$statement = $pdo->prepare($query);

$idArray = [1 , 2 , 3 , 4 , 5 , /** very long array, as your date list **/ ];
foreach($idArray as $id)
{
    $statement->execute(array(':id' => $id));
    $result = $statement->fetchAll();
}

N+1 问题

另一种方法是关于 N+1 问题。如果其他提示不足以加快速度，您可以使用本机函数 (array_map, array_walk, array_filter, etc...) 收集值并执行单个请求。

看看： What is SELECT N+1? https://secure.phabricator.com/book/phabcontrib/article/n_plus_one/

查询

最后，我需要有关您的查询的更多信息。您正在使用许多 mysql 函数。这是我得到的最后一个似是而非的暗示。但是，正如您所说，查询执行速度很快。尝试取出这些函数并检查脚本的执行是否得到改进。

更新

首先，我认为您在 MySQL 函数中使用了如此多的 PHP 变量。如果您只需要获取年份和月份 (yyyy-mm)，请使用 DateTime::format()。

$date->format('Y-m');//2017-02

手册上有很多例子。

正如我之前所说，prepared statement 是一种“预编译”查询。您必须使用占位符（命名或位置）而不是变量来编写查询。上面的查询就是我的例子：

$query = "SELECT *
    FROM
        mytable 
        INNER JOIN mysecondtable ON (mytable.id = mysecondtable.id_mytable)
    WHERE
        mytable.date BETWEEN :start AND :end
        AND mytable.value >= :value;";

你已经有了 foreach：

$data  = array();

$start = new DateTime('first monday of January 2016');
$end   = new DateTime('last day of December 2016');

$datePeriod = new DatePeriod($start , new DateInterval('P7D') , $end);

foreach($datePeriod AS $dates) {
    //your code
}

现在，您必须在 foreach 循环之外“准备”您的查询：

$statement = $this->db->prepare($query);
foreach($datePeriod AS $dates) {
    //your code
}

在你的 foreach 中，只需要使用占位符。

foreach($datePeriod AS $dates) {
    $values = [
        'start' => $dates->format('Y-m-d'),
        'end' => $dates->add(new DateInterval('P7D'))->format('Y-m-d'),//add 7 to reach a week
        'value' => 10
    ];

    $types = [
        'start' => Column::BIND_PARAM_STR,
        'end' => Column::BIND_PARAM_STR,
        'value' => Column::BIND_PARAM_INT
    ]

    //Phalcon PDO Adapter method
    $result = $connection->executePrepared($statement , $values , $types);//The result is a PDOStatement object

    $data[] = $result->fetchAll();
}

通过这些技巧，您可以大大缩短脚本的执行时间。

Answer 2

没有循环，几乎没有 PHP 代码，只有一个 SQL：

SELECT
       WEEK(date),
       AVG(...)
    FROM tbl
    JOIN ...
    WHERE date >= '2016-01-01'
      AND date  < '2016-01-01' + INTERVAL 1 YEAR
    GROUP BY week(date);

我可能遗漏了一些细节，但这可能会为您指明有助于简化代码的方向。

6 周前的星期一（从今天开始，即星期二）：

mysql> SET @d := CURDATE();
mysql> SELECT @d, DAYOFWEEK(@d), TO_DAYS(@d),
              TO_DAYS(@d + INTERVAL 2 DAY) - DAYOFWEEK(@d) AS ThisMon;
+------------+---------------+-------------+---------+
| @d         | DAYOFWEEK(@d) | TO_DAYS(@d) | ThisMon |
+------------+---------------+-------------+---------+
| 2017-02-07 |             3 |      736732 |  736731 |
+------------+---------------+-------------+---------+
mysql> SELECT FROM_DAYS(736731 - 6*7);
+-------------------------+
| FROM_DAYS(736731 - 6*7) |
+-------------------------+
| 2016-12-26              |
+-------------------------+