我不明白为什么CHARINDEX不工作

Question

我真的百思不得其解......

有人能告诉我为什么

charindex('\', REVERSE('test\henrov')) as char1, 
    charindex('\', REVERSE('test\henrov'))-1 as char2, 
    len(RIGHT('test\henrov', charindex('\', REVERSE('test\henrov'))))-1 as test, 
    right('test\henrov',6) as [OK], 
    right('test\henrov', charindex('\', REVERSE('test\henrov'))-1) as [ALSO_OK] 

作品和

charindex('\', REVERSE(m.username)) as char1, 
    charindex('\', REVERSE(m.username))-1 as char2, 
    len(RIGHT(m.username, charindex('\', REVERSE(m.username))))-1 as test, 
    right(m.username,6) as [OK], 
    right(m.username, charindex('\', REVERSE(m.username))-1) as [NOT_OK] 

不起作用？ m.username是一个varchar，其中包含'test \ henrov'.....

我收到一个错误：无效的长度参数传递给RIGHT函数。

Answer 1

笨！我发现这里的溶液：

SQL charindex throwing Invalid length parameter passed to the LEFT or SUBSTRING function because of period?

右（m.username，CHARINDEX（ '\'，反向（m.username）+ '\'）-1）为[OK_Yes]