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我首先要说的是（不幸地）设置了表结构。

max()我的目标是从查询中选择几个。假设我有以下表格

          jobReferenceTable                     jobList
 jobID | jobName  | jobDepartment |        listID |  jobID  |
_______|__________|_______________|        _______|_________|
   1   | dishes   |   cleaning    |          1    |    1    |
   2   |vacumming |   cleaning    |          2    |    5    |
   3   | mopping  |   cleaning    |          3    |    2    |
   4   |countMoney|     admin     |          4    |    4    |
   5   | hirePpl  |     admin     |          5    |    1    |
                                             6    |    2    |
                                             7    |    3    |
                                             8    |    3    |
                                             9    |    1    |
                                             10   |    5    |

不知何故，我想要一个查询，从清理中选择 jobID，然后显示每个作业的最新 jobList ID。我在下面开始了一个查询，下面是我希望得到的结果

询问

SELECT jrt.jobName, jrt.jobDepartment
FROM jobReferenceTable
WHERE jobDepartment = 'cleaning'
JOIN jobList jl ON jr.jobID = jl.jobID

结果

 jobName | jobDepartment | listID |
 ________|_______________|________|
    1    |    cleaning   |    9   |
    2    |    cleaning   |    6   |
    3    |    cleaning   |    8   |
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1 回答 1

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尝试这个;

SELECT jrt.jobName, jrt.jobDepartment, MAX(jl.listID)
FROM jobReferenceTable AS jrt INNER JOIN jobList AS jl ON jrt.jobID = jl.jobID
WHERE jrt.jobDepartment = 'cleaning'
GROUP BY jrt.jobName, jrt.jobDepartment

据我所知，您只需要一个MAX()- listID.

MAX()是一个聚合函数，这意味着您的结果集的其余部分必须被“分组”。

于 2013-04-26T22:19:35.260 回答