Replacing variable length string with some word

Question

Given the below string

Declare @string varchar(max)=\'abc ___________ deffns ___ cg _ hif _______hh ihs\';

this is the Output requi

Answer 1

First get rid of the multiple underscores, then do the replace.

Here is one method:

select replace(replace(replace(@string, '_', '><'
                              ), '<>', ''
                      ), '><', 'LASTNAME'
              )

Answer 2

In C# you can use:

string str = Regex.Replace(s, @"(_)\1{5,}", Lastname);

It will match character _ if more than 5 _ occurs.