在SQL中使用字符串的一部分搜索匹配的字符串

Question

I current have one table whereby with a unique index of 'col_0' I have the same set of data for 2 different indexes. The problem is the copy function in my application automatically cuts of the description and adds "copied from at the end".

Example

Col_0 Description
A This is a very annoying application problem
B This is a very annoy (Copied from column a)

I just wanted to search for and then update B so it matches I've tried join it by part of the description.

So far I've tried CHARINDEX but I can't quite get it right.

Answer 1

I read your request thus: "Copied from column a)" means copied from the description of the record with col_0 = 'A'. And you want to update all "copied from .." descriptions with their original description.

In order to find the "copied from .." records I am using LIKE. To extract the col_0 value from the string I am using some string functions (mainly REVERSE + CHARINDEX to find the last occurrence of a blank and then SUBSTRING for the extraction).

update mytable upd
set description =
(
 select description
 from mytable orig
 where orig.col_0 = 
   substring(upd.description, 
             len(upd.description) - charindex(' ', reverse(upd.description)) + 2, 
             charindex(' ', reverse(upd.description) - 2
            )
)
where description like '%(Copied from column %)';