如何在 SQL 中具有未确定模式的字符串中的两个字符之间提取 substring

Question

I have read a lot of topics discussing extracting substring between two characters but my problem is a bit different than the existing ones. I have a string like this with different patterns ''' /m/ hello end; /r/ how are you end; '''

I need to separate strings between /m/ and end; and between /r/ and end;

I have used substring and charindex functions which give correct output BUT NOT in all cases of input string. My input string has too many variation.eg it could be like ''' /m/ hello /r/ how are you end; (no end in /m/ part) ''' in this case if I extract string between /m/ and end; it will include /r/ which I don't need. if I change the logic and extract between /m/ and /r/ then /r/ could be before /m/ eg

''' /r/ I am working from home during this pandemic end; /m/ how about you end; /r/ before /m/) ''' input string has nor definite length.

Tried to use PATINDEX but my input string has no specific pattern.

I need expert's advice.

Thanks for your help!

Answer 1

This splits the string by replacing both /m/ and /r/ with a pipe '|'and then using STRING_SPLIT on the result.

declare @string         varchar(100)=''' /m/ hello end; /r/ how are you end; ''';

select @string=replace(@string, t.v, '|')
from
  (values ('/m/'), ('/r/')) t(v);

select trim([value]) split_string from string_split(@string, '|');

UPDATED: To retain the two search terms inside @string it uses nested REPLACE functions. To retain the ordering of the appearance of the search terms I used this splitter.

declare @string         varchar(100)=''' /m/ hello end; /r/ how are you end; ''';

select * from dbo.DelimitedSplit8K(replace(replace(@string,'/m/', '|/m/'),'/r/', '|/r/'), '|');