Question

我有以下查询，我使用相同的子查询4次，这影响了我的性能。有没有办法重用子查询只运行一次并在我需要的其他地方引用它？

下面是代码，感谢

SELECT adb_product_type.strproduct_type AS strproduct_type, adb_product_cat.strproduct_cat AS strproduct_cat, adb_product.strproduct AS strproduct, 

CASE 
(SELECT COUNT(DISTINCT adb_campaign_1.campaign_id) 
FROM adb_camp_media AS adb_camp_media_1 
INNER JOIN adb_campaign AS adb_campaign_1 ON adb_campaign_1.campaign_id = adb_camp_media_1.campaign_id 
WHERE adb_camp_media_1.lngproduct = adb_camp_media.lngproduct 
AND adb_camp_media_1.lngproduct = adb_camp_media.lngproduct 
AND ((adb_campaign_1.start_date >= '2010-01-01' AND adb_campaign_1.start_date <= '2010-01-31') 
OR (adb_campaign_1.end_date >= '2010-01-01' AND adb_campaign_1.end_date <= '2010-01-31')) )
WHEN 0 THEN 'No' ELSE 'Yes'
END AS 'YesNo', 

CASE 
(SELECT COUNT(DISTINCT adb_campaign_1.campaign_id) 
FROM adb_camp_media AS adb_camp_media_1 
INNER JOIN adb_campaign AS adb_campaign_1 ON adb_campaign_1.campaign_id = adb_camp_media_1.campaign_id 
WHERE adb_camp_media_1.lngproduct = adb_camp_media.lngproduct 
AND adb_camp_media_1.lngproduct = adb_camp_media.lngproduct 
AND ((adb_campaign_1.start_date >= '2010-01-01' AND adb_campaign_1.start_date <= '2010-01-31') 
OR (adb_campaign_1.end_date >= '2010-01-01' AND adb_campaign_1.end_date <= '2010-01-31')) )
WHEN 0 THEN '' ELSE 

(SELECT COUNT(DISTINCT adb_campaign_1.campaign_id) 
FROM adb_camp_media AS adb_camp_media_1 
INNER JOIN adb_campaign AS adb_campaign_1 ON adb_campaign_1.campaign_id = adb_camp_media_1.campaign_id 
WHERE adb_camp_media_1.lngproduct = adb_camp_media.lngproduct 
AND adb_camp_media_1.lngproduct = adb_camp_media.lngproduct 
AND ((adb_campaign_1.start_date >= '2010-01-01' AND adb_campaign_1.start_date <= '2010-01-31') 
OR (adb_campaign_1.end_date >= '2010-01-01' AND adb_campaign_1.end_date <= '2010-01-31')) )
END AS 'CampaignCount', 

CASE
(SELECT COUNT(DISTINCT adb_campaign_1.campaign_id) 
FROM adb_camp_media AS adb_camp_media_1 
INNER JOIN adb_campaign AS adb_campaign_1 ON adb_campaign_1.campaign_id = adb_camp_media_1.campaign_id 
WHERE adb_camp_media_1.lngproduct = adb_camp_media.lngproduct 
AND adb_camp_media_1.lngproduct = adb_camp_media.lngproduct 
AND ((adb_campaign_1.start_date >= '2010-01-01' AND adb_campaign_1.start_date <= '2010-01-31') 
OR (adb_campaign_1.end_date >= '2010-01-01' AND adb_campaign_1.end_date <= '2010-01-31')) )
WHEN 0 THEN '' ELSE 
 adb_media.name 
END AS mediaName

FROM adb_product_type 
LEFT JOIN adb_product_cat ON adb_product_cat.lngproduct_type = adb_product_type.lngproduct_type 
LEFT JOIN adb_product ON adb_product.lngproduct_cat = adb_product_cat.lngproduct_cat 
LEFT JOIN adb_camp_media ON adb_camp_media.lngproduct = adb_product.lngproduct 
LEFT JOIN adb_media ON adb_media.media_id = adb_camp_media.media_id 
LEFT JOIN adb_camp_media_prod ON adb_camp_media_prod.media_num = adb_camp_media.media_num 
LEFT JOIN adb_campaign ON adb_campaign.campaign_id = adb_camp_media.campaign_id 
WHERE 1=1 AND (adb_campaign.start_date >= '2010-01-01' AND adb_campaign.start_date <= '2010-01-31') 
OR (adb_campaign.end_date >= '2010-01-01' AND adb_campaign.end_date <= '2010-01-31')
OR ( adb_camp_media.campaign_id IS NULL) OR (adb_camp_media_prod.lngproduct IS NULL)

GROUP BY strproduct, mediaName ORDER BY strproduct_type, strproduct_cat, strproduct

Answer 1

我发现它...在mysql中你可以使用用户变量，例如。

@campaignCount:=(SELECT 
                  COUNT(DISTINCT adb_campaign_1.campaign_id) 
                  FROM adb_camp_media AS adb_camp_media_1 
                   INNER JOIN adb_campaign AS adb_campaign_1 
                    ON adb_campaign_1.campaign_id = adb_camp_media_1.campaign_id 
                   WHERE adb_camp_media_1.lngproduct = adb_camp_media.lngproduct 
                    AND ((adb_campaign_1.start_date >= '2010-01-01' 
                    AND adb_campaign_1.start_date <= '2010-01-31') 
                    OR (adb_campaign_1.end_date >= '2010-01-01' 
                    AND adb_campaign_1.end_date <= '2010-01-31')) )

Answer 2

您可以提取子查询的结果并将其放在临时表中。然后更新您的查询以使用临时表的内容。

我如何在mysql中重用子查询？

2 个答案: