Remove Substring according to specific pattern - sql

Question

I need to remove in a SQL Server database a substring according to a pattern:
Before: Winter_QZ6P91712017_115BPM
After: Winter_115BPM
Or
Before: cpx_Note In My Calendar_QZ6P91707044
After: cpx_Note In My Calendar
Basically delete the substring that has pattern _ + 12 chars.
I've tried PatIndex('_\S{12}', myCol) to get the index of the substring but it doesn't match anything.

Answer 1

Assuming you mean underscore followed by 12 characters that are not underscores you can use this pattern:
SELECT *,
CASE WHEN PATINDEX('%[_][^_][^_][^_][^_][^_][^_][^_][^_][^_][^_][^_][^_]%', str) > 0
THEN STUFF(str, PATINDEX('%[_][^_][^_][^_][^_][^_][^_][^_][^_][^_][^_][^_][^_]%', str), 13, '')
ELSE str
END
FROM (VALUES
('Winter_QZ6P91712017_115BPM'),
('Winter_115BPM_QZ6P91712017')
) AS tests(str)

Answer 2

late to the party, but you could also use latest STRING_SPLIT function to explode the string by underscores and count length of each segment between underscores. If the length is >=12, these sections must be replaced from original string via replace function recursively.
drop table if exists Tbl;
drop table if exists #temptable;
create table Tbl (input nvarchar(max));
insert into Tbl VALUES
('Winter_QZ6P91712017_115BPM'),
('cpx_Note In My Calendar_QZ6P91707044'),
('stuff_asdasd_QZ6P91712017'),
('stuff_asdasd_QZ6P91712017_stuff_asdasd_QZ6P91712017'),
('stuff_asdasd_QZ6P917120117_stuff_asdasd_QZ6P91712017');
select
input, value as replacethisstring,
rn = row_number() over (partition by input order by (select 1))
into #temptable
from
(
select
input,value as hyphensplit
from Tbl
cross apply string_split(input,'_')
)T cross apply string_split(hyphensplit,' ')
where len(value)>=12
; with cte as (
select input, inputtrans= replace(input,replacethisstring,''), level=1 from #temptable where rn=1
union all
select T.input,inputtrans=replace(cte.inputtrans,T.replacethisstring,''),level=level+1
from cte inner join #temptable T on T.input=cte.input and rn=level+1
--where level=rn
)
select input, inputtrans
from (
select *, rn=row_number() over (partition by input order by level desc) from cte
) T where rn=1
sample output

Answer 3

SQL Server doesn't support Regex. Considering, however, you just want to remove the first '_' and the 12 characters afterwards, you could use CHARINDEX to find the location of said underscore, and then STUFF to remove the 13 characters:
SELECT V.YourString,
STUFF(V.YourString, CHARINDEX('_',V.YourString),13,'') AS NewString
FROM (VALUES('Winter_QZ6P91712017_115BPM'))V(YourString);