Question

    SELECT *
    FROM
    construction AS T2
    INNER JOIN  
    (
      SELECT   project,MAX(report_date)
       FROM construction 
            GROUP BY project
     ) AS R 

     ON T2.project=R.project AND T2.report_date=R.report_date

收到此错误。请帮助没有为'R'

的第2列指定列名

Answer 1

您需要为SELECT * FROM construction AS T2 INNER JOIN ( SELECT project,MAX(report_date) AS report_date FROM construction GROUP BY project ) AS R ON T2.project = R.project AND T2.report_date = R.report_date;添加别名：

SQL Server

在SELECT * FROM construction AS T2 INNER JOIN ( SELECT project,MAX(report_date) FROM construction GROUP BY project ) AS R(project, report_date) ON T2.project = R.project AND T2.report_date = R.report_date;中，您可以使用语法：

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Answer 2

您应该使用别名MAX(report_date)来指定report_date 因为您的表格R有两列project,MAX(report_date)。

Answer 3

您收到此错误是因为您没有为内部查询指定列名

您必须将查询编写为

SELECT * 从建筑 INNER JOIN
（ SELECT项目，MAX（report_date）“Max_ReportDate” 从建筑 GROUP BY项目）Max_construction ON construction.project = Max_construction .project AND construction.report_date = Max_construction .Max_ReportDate

内部联接表自己没有为第2列

3 个答案: