小编Chh*_*aal的帖子

有这个统一教程称为太空射击游戏,由于某种原因,我得到以下错误:

AppData/Local/Unity/cache/packages/packages.unity.com/com.unity.package-manager-ui@2.0.3/Editor/Sources/Services/Upm/UpmBaseOperation.cs(34,43): 
error CS1061: Type 'UnityEditor.PackageManager.PackageInfo' does not contain a definition for 'author' and no extension method 'author' of type 'UnityEditor.PackageManager.PackageInfo' could be found.
Are you missing an assembly reference?

它只是项目的开始,我甚至没有编写任何脚本.我不知道这是什么意思.

据我所知,在两个表之间的左外连接(比如a和b)中,无论右表中行的值如何,都会检索连接左侧表的所有行.那么为什么我们需要一个'ON'子句来指定一个条件,如下所示:

select * from a LEFT OUTER JOIN b on a.some_column1 = b.some_column2;

为什么需要声明"a.some_column1 = b.some_column2".