在SQL中将数据字符串的一部分从一列复制到另一列

Question

Table and (columns) in question are:

Attachment (att_name and att_path)

I make this call to Select the info I want to update:

select * from attachment
where att_path like '%//bahamas/attachments/images/logos/%'

I need to update the att_name column with the filename in the path above. For example, if SQL finds "//bahamas/attachments/images/logos/ ABCDE.tif " I need SQL to update the att_name to replace whatever is currently in there and insert ABCDE.tif

I have tried multiple different test's on just one item and I can't seem to get my SQL correct to implement a global call where this update runs on all rows where att_path like '%//bahamas/attachments/images/logos/%'

Any advise/help is greatly appreciated.

Answer 1

update attachment set
       att_name = Right(att_path, CharIndex('/', Reverse(att_path)) - 1)
 where att_path like '%//bahamas/attachments/images/logos/%'

should do what you want. Reversing and then searching the first occurrence of / in effect searches from the end.

Before running the update, however, I usually run a select to check if I hit the correct character positions when developing statements like the following, as it is easy to get off-by-one errors with string manipulations:

select att_path, Right(att_path, CharIndex('/', Reverse(att_path)) - 1)
  from attachment
 where att_path like '%//bahamas/attachments/images/logos/%'