Question

我有以下MySQL声明：

SELECT gls.id AS glid, gls.gl, gls.name AS gl_name, requests.costCenter, budgets.total as totalBudgeted,
                    ROUND(SUM(CASE WHEN requests.ap = 1 THEN totalCost ELSE 0 END), 2) AS ap1, 
                    ROUND(SUM(CASE WHEN requests.ap = 2 THEN totalCost ELSE 0 END), 2) AS ap2,
                    ROUND(SUM(CASE WHEN requests.ap = 3 THEN totalCost ELSE 0 END), 2) AS ap3,
                    ROUND(SUM(CASE WHEN requests.ap = 4 THEN totalCost ELSE 0 END), 2) AS ap4,
                    ROUND(SUM(CASE WHEN requests.ap = 5 THEN totalCost ELSE 0 END), 2) AS ap5,
                    ROUND(SUM(CASE WHEN requests.ap = 6 THEN totalCost ELSE 0 END), 2) AS ap6,
                    ROUND(SUM(CASE WHEN requests.ap = 7 THEN totalCost ELSE 0 END), 2) AS ap7,
                    ROUND(SUM(CASE WHEN requests.ap = 8 THEN totalCost ELSE 0 END), 2) AS ap8,
                    ROUND(SUM(CASE WHEN requests.ap = 9 THEN totalCost ELSE 0 END), 2) AS ap9,
                    ROUND(SUM(CASE WHEN requests.ap = 10 THEN totalCost ELSE 0 END), 2) AS ap10,
                    ROUND(SUM(CASE WHEN requests.ap = 11 THEN totalCost ELSE 0 END), 2) AS ap11,
                    ROUND(SUM(CASE WHEN requests.ap = 12 THEN totalCost ELSE 0 END), 2) AS ap12 
                FROM gls
                    LEFT JOIN requests ON requests.glid = gls.id 
                    LEFT JOIN budgets ON budgets.gl = gls.id AND budgets.costCenter = 2
                WHERE requests.status = 'approved' AND requests.costCenter = 2
                    GROUP BY gls.id

我的问题是，当我运行查询时，我只会得到与其相关的请求的＆＃34; gl＆＃34; s。＆＃34; gl＆＃34; s不会在请求表中显示相应的条目。

我尝试了一些JOINS的排列，但似乎没有任何效果。对我来说很明显，限制因素是阻止所有GL显示的LEFT JOIN requests ON requests.glid = gls.id，但据我所知，LEFT JOIN应保留所有GL表值，并且只添加相应的REQUESTS值。

出于隐私原因，我无法显示任何数据，但我可以尝试总结一下：

在gls表中有30行，

在请求表中，可以有任意数量的行，但每个行都有一个外键将它们链接到gls表中的一行。基本上，我的查询应该给我一张所有gls的表格，并标记旁边相应请求的信息。

此外，我感觉有人在这里可以清理这个查询并使其更短，更短。

谢谢大家！

Answer 1

你对LEFT JOIN是正确的。问题是你的WHERE：

WHERE requests.status = 'approved' AND requests.costCenter = 2

这会过滤掉没有请求的所有行。

相反，您希望将该条件移至JOIN：

LEFT JOIN requests 
  ON requests.glid = gls.id 
 AND requests.status = 'approved' AND requests.costCenter = 2

如何合并来自2个表的数据，包括不匹配的字段

1 个答案: