Question

我有一个SQL查询，用于显示带分页和排序顺序的数据列表。排序顺序有一个＆＃34; IN＆＃34;在树中查询以显示更准确的数据。

以下是代码：

SELECT 
  s.ID id_sent, 
  SendingDateTime, 
  DestinationNumber, 
  TextDecoded, 
  UDH, 
  id_folder, 
  Status, 
  p.ID id_pbk, 
  Name, 
  Number
FROM 
  sentitems s LEFT JOIN pbk p 
    ON p.Number = s.DestinationNumber
WHERE 
  `id_folder` = 3
  AND `Status` IN ('SendingOK',  'SendingOKNoReport')
  AND SendingDateTime IN (
                            SELECT 
                              MAX(SendingDateTime) 
                            FROM sentitems
                            WHERE 
                              id_folder = '3'
                              AND `Status` IN ('SendingOK',  'SendingOKNoReport')
                            GROUP BY DestinationNumber
                         )
ORDER BY `SendingDateTime` DESC LIMIT $posisi,$batas

我的问题是，当我在sentitems表中有很多数据时; ex 3000数据，虽然我限制20个数据显示。该页面确实需要很长时间才能加载然后超时。

我的问题是，是否可以改进我的查询？或者是否有任何其他方式来显示我的数据结果与我的查询完全相同？

提前致谢

Answer 1

这可能适合你

SELECT s.ID id_sent, SendingDateTime, DestinationNumber, TextDecoded, UDH, id_folder, Status, p.ID id_pbk, Name, Number
                FROM sentitems s
                LEFT JOIN pbk p ON p.Number = s.DestinationNumber
                inner join
                (

                  SELECT MAX(SendingDateTime)  as maxSendingDateTime
                      FROM sentitems
                      WHERE id_folder = '3'
                      AND `Status` 
                      IN (
                          'SendingOK',  'SendingOKNoReport'
                      )
                      GROUP BY DestinationNumber
                ) c as c.maxSendingDateTime = maxSendingDateTime
                WHERE `id_folder` = 3
                AND `Status` 
                IN (
                    'SendingOK',  'SendingOKNoReport'
                )
                ORDER BY `SendingDateTime` DESC
                LIMIT $posisi,$batas;

Answer 2

我的猜测是减速是IN语句，你正在查看MAX（SendingDateTime）列表。相反，您可以尝试使用另一个WHERE子句解析该列表。所以它会是这样的：

SELECT 
  s.ID id_sent, 
  SendingDateTime, 
  DestinationNumber, 
  TextDecoded, 
  UDH, 
  id_folder, 
  Status, 
  p.ID id_pbk, 
  Name, 
  Number
FROM 
  sentitems s LEFT JOIN pbk p 
    ON p.Number = s.DestinationNumber
WHERE 
  `id_folder` = 3
  AND `Status` IN ('SendingOK',  'SendingOKNoReport')
  AND SendingDateTime = (
                            SELECT 
                            MAX(SendingDateTime) 
                            FROM sentitems si
                            WHERE 
                              si.id_folder = '3'
                            AND s.Destination = si.Destination
                              AND si.`Status` IN ('SendingOK',  'SendingOKNoReport')
                            GROUP BY DestinationNumber
                         )
ORDER BY `SendingDateTime` DESC LIMIT $posisi,$batas

MySQL Query真的需要很长时间才能加载然后获得超时

2 个答案: