mysql - 联合与内连接，mysql错误

Question

(SELECT * FROM app_detailsvvv as dtable INNER JOIN new_apps ON 
new_apps.trackId=dtable.trackId WHERE primaryGenreName='Games'
AND composed='1' AND new_apps.top>0)
UNION (SELECT * FROM app_detailsvvv as dtable WHERE primaryGenreName='Games')
LIMIT 12

错误:

#1222 - The used SELECT statements have a different number of columns

在 new_apps 上，有些字段不在 app_detailsvvv 中，我如何以某种方式屏蔽联合中的第二个查询。

编辑:

(SELECT dtable.* FROM app_detailsvvv as dtable INNER JOIN new_apps ON new_apps.trackId=dtable.trackId WHERE primaryGenreName='Games' AND composed='1' AND new_apps.top>0) UNION (SELECT * FROM app_detailsvvv as dtable WHERE primaryGenreName='Games') LIMIT 12

当我添加 ORDER BY new_apps.top ASC 时，我收到了这个新错误:

#1250 - Table 'new_apps' from one of the SELECTs cannot be used in global ORDER clause

Answer 1

我认为您不需要联合，只需一个左外连接:

SELECT dtable.*
FROM app_detailsvvv as dtable LEFT OUTER JOIN
     new_apps
     ON new_apps.trackId = dtable.trackId and
        composed = '1' AND new_apps.top > 0
WHERE dtable.primaryGenreName = 'Games'
LIMIT 12;

嗯，这可能会返回重复项，您可以使用 select different dtable.* 删除重复项。

但是等等。除了返回第一个表中的所有行之外，该查询实际上没有执行任何操作。我怀疑您想要返回 12 行，并优先考虑匹配的行。如果是这种情况，那么您想要的查询是:

SELECT dtable.*
FROM app_detailsvvv as dtable LEFT OUTER JOIN
     new_apps
     ON new_apps.trackId = dtable.trackId
WHERE dtable.primaryGenreName = 'Games'
GROUP BY dtable.trackId   <-- or whatever the unique id is on the table
ORDER BY (composed = '1' AND new_apps.top > 0) desc
LIMIT 12;