what I would like to do is to add several sequence numbers to one single sql view in MySQL. Consider the following example table:
Folder 1, File 1
Folder 1, File 2
Folder 2, File 3
Folder 3, File 4
Folder 3, File 5
Folder 3, File 6
因此，我希望得到的结果是：
1, Folder 1, File 1
2, Folder 1, File 2
1, Folder 2, File 3
1, Folder 3, File 4
2, Folder 3, File 5
3, Folder 3, File 6
我知道如何使用变量将一个序列号添加到整个视图中，但我不知道如何解决我的特定问题。希望有人能帮我。
非常感谢！
Cheers, Johannes
您将需要两个变量，而不是使用一个变量，而是在组更改时重置行编号。
select folder, file,
@r = case when @g = folder then @r+1 else 1 end SequenceNo,
@g := folder
from (select @g:=null) g
cross join tbl
order by folder, file
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