sql server - Need to insert breaks in strings of very column with ' ' or ',' -

i have table has 1 column on 100,000 rows
col_name qwchijhuirhxnihdiuyfnx

         dhjhfiurhncnmxmzjcoinrds           xnbxknsiiuncirnxknrxnxz 

i need insert '.' or '$' or marker after every 3rd character

example of result needed:

         col_name          qwc.hij.hui.rhx.nih.diu.yfn.x          dhj.hfi.urh.ncn.mxm.zjc.oin.rds.          xnb.xkn.sii.unc.irn.xkn.rxn.xz 

i solved with:

insert new_table ( c1 ,c2 ,c3 ) select       substring(cast(col_name varchar(max)),1,3) c1      ,substring(cast(col_name varchar(max)),4,3) c2      ,substring(cast(col_name varchar(max)),7,3) c3      table_name 

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this causes problems later in script data must remain in 1 column inserted new table long new table 1 column

here's sqlfiddle starting point can refactor http://sqlfiddle.com/#!6/ab6dd/1/0 using function , while loop.

you may able more efficient regular expressions or sqlclr if need speed.

create function dotify (@input varchar(max)) returns varchar(max) begin  declare @output varchar(max) = ''  declare @index int = 0 declare @length int set @length = len(@input) while @index <= @length begin  set @output = @output + substring(@input, @index, 1)  if (@index % 3) = 0 , @index > 0  begin    set @output = @output +'.'  end  set @index = @index + 1 end return(@output) end go select top 10000 col_name, dbo.dotify(col_name)  old_table 

you can use top limit processing time few seconds can profile efficiency changes make.