mysql-链接到另一个表以使用内部联接获取名称

以下代码显示了一个项目的最大日期,并且一切正常.

    SELECT 
    pricing_id, pricing.field, pricing.region, price, max_date
FROM
    pricing
        INNER JOIN
    (SELECT 
        field, MAX(end_date) AS 'max_date'
    FROM
        pricing, regions
    GROUP BY field) AS tmptable ON tmptable.max_date = pricing.end_date
        AND tmptable.field = pricing.field
ORDER BY region, pricing.field

我正在尝试从regions.region_name中提取区域名称以替换仅显示ID的priceing.region列.我已经尝试了通常的where子句来联接表并显示描述性名称,但是它破坏了它.

有人可以帮忙吗？

谢谢,

约翰

解决方法:

您必须从地区表中选择region_name

像

SELECT 
pricing_id, pricing.field, tmptable.region_name , price, max_date
FROM
pricing
    INNER JOIN
(SELECT 
   region_name , field, MAX(end_date) AS 'max_date'
FROM
    pricing, regions
GROUP BY field) AS tmptable ON tmptable.max_date = pricing.end_date
    AND tmptable.field = pricing.field
ORDER BY region, pricing.field

应该管用.

标签：inner-join,mysql,database
来源： https://codeday.me/bug/20191026/1934694.html