Question

我有以下两个表

1. publisher_site_regionwise_adratio
publisher_id | site    | region | ad_ratio | product_code
=========================================================
001          | xyz.com | US     | 8:2      | TB

和

2. publisher_site_regionwise_info
publisher_id | site    | region | regional_keywords
=======================================================
001          | xyz.com | US     | business, warehouse

现在第二个表的数据不是product_code明智的。站点的区域信息与具有特定区域的特定站点的发布者的product_code无关。现在我想要一个能给我以下字段的查询

site    | region | ad_ratio | has_regional_info
============================================
xyz.com | US     | 8:2      | 1

has_regional_info列将具有0或1，具体取决于特定区域中的网站是否已映射regional_keywords。

我无法想象如何使用JOIN并获得这样的结果。任何帮助将非常感激。

Answer 1

我会在您的信息表格中加入一个简单的JOIN，然后检查regional_keywords列中是否有数据来确定{1}}的1或0

has_regional_info

如果SELECT ar.site, ar.region, ar.ad_ratio , CASE WHEN i.regional_keywords IS NOT NULL THEN 1 ELSE 0 END AS has_regional_info FROM publisher_site_regionwise_adratio AS ar LEFT JOIN publisher_site_regionwise_info AS i ON ar.publisherId = i.publisherId和publisher_site_regionwise_adratio之间的外键不仅仅是publisher_site_regionwise_info（在您的示例中难以分辨3个重复的列），那么只需将它们添加到{{1}连接语句如：publisherId

Answer 2

SELECT ratio.site, ratio.region, ratio.ad_ration,
    IF(info.has_regional_info IS NULL, true, false)
FROM publisher_site_regionwise_adratio AS ratio
LEFT JOIN publisher_site_regionwise_info AS info
    ON ratio.publisher_id = info.publisher_id

Answer 3

select publisher_site_regionwise_adratio.site,  
       publisher_site_regionwise_adratio.region,
       publisher_site_regionwise_adratio.ad_ratio,
       LENGTH(regional_keywords)>0 as has_regional_info
          from publisher_site_regionwise_adratio 
            join publisher_site_regionwise_info.publisher_id 
              on publisher_site_regionwise_adratio.publisher_id 
                 = publisher_site_regionwise_info.publisher_id

Answer 4

这应该做：

SELECT a.publisher_id, a.site, a.ad_ratio,
    i.regional_keywords IS NOT NULL AS has_regional_keywords
FROM publisher_site_regionwise_adratio a, publisher_site_regionwise_info i
WHERE a.publisher_id = i.publisher_id;

mysql中的条件字段连接查询结果

4 个答案: