如何用sql查詢替換給定字符串中的特定字符數？

Question

像：

s1= 'ldoed@dldkeo@fkfok@dkf@' 

像 'ldoedKdldkeo @ fkfokKdkf @' 輸出

替換從字符串的字符 'K'

Answer 1

第一@和第三@試試這個使用charindex()和stuff()：

Fiddle demo 1

declare @s1 varchar(100)= 'ldoed@dldkeo@fkfok@dkf@', @count int = 0 

select @count = charindex('@',@s1,@count+1), 
     @s1 = case isremove when 1 then 
      stuff(@s1, charindex('@',@s1,@count) ,1,'K') else @s1 end 
from (values (1),(0),(1)) t(isremove) 

Fiddle demo 2

declare @s1 varchar(100)= 'ldoed@dldkeo@fkfok@dkf@' 

select stuff(stuff(@s1,first,1,'K'),third,1,'K') 
from (
select charindex('@',@s1,1) first, 
    charindex('@',@s1,charindex('@',@s1,charindex('@',@s1,1)+ 1)+1) third 
)x