how to modify t-sql to process multiple records not just one. - sql

Question

I am working on a function to remove/ replace special characters from a string from a column named "Title". Currently I am testing the code for one record at a time. I would like to test the code against all the records in the table, but I do not know how to modify the current t-sql to process all the records rather than just one at a time. I would appreciate if someone could show me how, or what type of modifications I need to do to be able to process all records.
This is the code as I have it right now:
DECLARE #str VARCHAR(400);
DECLARE #expres VARCHAR(50) = '%[~,#,#,$,%,&,*,(,),.,!,´,:]%'
SET #str = (SELECT REPLACE(REPLACE(LOWER([a].[Title]), CHAR(9), ''), ' ', '_') FROM [dbo].[a] WHERE [a].[ID] = '43948')
WHILE PATINDEX(#expres, #str) > 0
SET #str = REPLACE(REPLACE(#str, SUBSTRING(#str, PATINDEX(#expres, #str), 1), ''), '-', ' ')
SELECT #str COLLATE SQL_Latin1_General_CP1251_CS_AS
For a Title containing the value: Schöne Wiege Meiner Leiden, the output after the code is applied would be: schone_wiege_meiner_leiden
I would like to make the code work to process multiple records rather that one like is done currently by specifying the ID. I want to process a bulks of records.
I hope I can get some help, thank you in advance for your help.
Code example taken from: remove special characters from string in sql server

Answer 1

There is no need for a loop here. You can instead use a tally table and this can become a set based inline table valued function quite easily. Performance wise it will blow the doors off a loop based scalar function.
I keep a tally table as a view in my system. Here is the code for the tally table.
create View [dbo].[cteTally] as
WITH
E1(N) AS (select 1 from (values (1),(1),(1),(1),(1),(1),(1),(1),(1),(1))dt(n)),
E2(N) AS (SELECT 1 FROM E1 a, E1 b), --10E+2 or 100 rows
E4(N) AS (SELECT 1 FROM E2 a, E2 b), --10E+4 or 10,000 rows max
cteTally(N) AS
(
SELECT ROW_NUMBER() OVER (ORDER BY (SELECT NULL)) FROM E4
)
select N from cteTally
Now comes the fun part, using this to parse strings and all kinds of various things. It has been dubbed the swiss army knife of t-sql. Anytime you start thinking loop, try to think about using a tally table instead. Here is how this function might look.
create function RemoveValuesFromString
(
#SearchVal nvarchar(max)
, #CharsToRemove nvarchar(max)
) returns table as
RETURN
with MyValues as
(
select substring(#SearchVal, N, 1) as MyChar
, t.N
from cteTally t
where N <= len(#SearchVal)
and charindex(substring(#SearchVal, N, 1), #CharsToRemove) = 0
)
select distinct MyResult = STUFF((select MyChar + ''
from MyValues mv2
order by mv2.N
FOR XML PATH(''),TYPE).value('.','NVARCHAR(MAX)'), 1, 0, '')
from MyValues mv
;
Here is an example of how you might be able to use this. I am using a table variable here but this could be any table or whatever.
declare #SomeTable table
(
SomeTableID int identity primary key clustered
, SomeString varchar(max)
)
insert #SomeTable
select 'This coffee cost $32.!!! This is a# tot$#a%l r)*i-p~!`of^%f' union all
select 'This &that'
select *
from #SomeTable st
cross apply dbo.RemoveValuesFromString(st.SomeString, '%[~,##$%&*()!´:]%`^-') x