How to change case in string - sql

Question

My table has one column that contain strings like: ” HRM_APPLICATION_DELAY_IN”
I want to perform bellow operations on each row on this column
convert to lower case
remove underscore “_”
change case (convert to upper case) of the character after the underscore like: ” hrm_Application_Delay_In”
Need help for conversion. Thanks for advance

Answer 1

Here is a function to achieve it:
create function f_test
(
#a varchar(max)
)
returns varchar(max)
as
begin
set #a = lower(#a)
while #a LIKE '%\_%' ESCAPE '\'
begin
select #a = stuff(#a, v, 2, upper(substring(#a, v+1,1)))
from (select charindex('_', #a) v) a
end
return #a
end
Example:
select dbo.f_test( HRM_APPLICATION_DELAY_IN')
Result:
hrmApplicationDelayIn
To update your table here is an example how to write the syntax with the function:
UPDATE <yourtable>
SET <yourcolumn> = dbo.f_test(col)
WHERE <yourcolumn> LIKE '%\_%' ESCAPE '\'

Answer 2

For a variable this is overkill, but I'm using this to demonstrate a pattern
declare #str varchar(100) = 'HRM_APPLICATION_DELAY_IN';
;with c(one,last,rest) as (
select cast(lower(left(#str,1)) as varchar(max)),
left(#str,1), stuff(lower(#str),1,1,'')
union all
select one+case when last='_'
then upper(left(rest,1))
else left(rest,1) end,
left(rest,1), stuff(rest,1,1,'')
from c
where rest > ''
)
select max(one)
from c;
That can be extended to a column in a table
-- Sample table
declare #tbl table (
id int identity not null primary key clustered,
str varchar(100)
);
insert #tbl values
('HRM_APPLICATION_DELAY_IN'),
('HRM_APPLICATION_DELAY_OUT'),
('_HRM_APPLICATION_DELAY_OUT'),
(''),
(null),
('abc<de_fg>hi');
-- the query
;with c(id,one,last,rest) as (
select id,cast(lower(left(str,1)) as varchar(max)),
left(str,1), stuff(lower(str),1,1,'')
from #tbl
union all
select id,one+case when last='_'
then upper(left(rest,1))
else left(rest,1) end,
left(rest,1), stuff(rest,1,1,'')
from c
where rest > ''
)
select id,max(one)
from c
group by id
option (maxrecursion 0);
-- result
ID COLUMN_1
1 hrm_Application_Delay_In
2 hrm_Application_Delay_Out
3 _Hrm_Application_Delay_Out
4
5 (null)
6 abc<de_Fg>hi

Answer 3

select
replace(replace(replace(replace(replace(replace(replace(
replace(replace(replace(replace(replace(replace(replace(
replace(replace(replace(replace(replace(replace(replace(
replace(replace(replace(replace(replace(replace(lower('HRM_APPLICATION_DELAY_IN'),'_a','A'),'_b','B'),'_c','C'),'_d','D'),'_e','E'),'_f','F'),
'_g','G'),'_h','H'),'_i','I'),'_j','J'),'_k','K'),'_l','L'),
'_m','M'),'_n','N'),'_o','O'),'_p','P'),'_q','Q'),'_r','R'),
'_s','S'),'_t','T'),'_u','U'),'_v','V'),'_w','W'),'_x','X'),
'_y','Y'),'_z','Z'),'_','')

Answer 4

Bellow two steps can solve problem,as example i use sys.table.user can use any one
declare #Ret varchar(8000), #RetVal varchar(8000), #i int, #count int = 1;
declare #c varchar(10), #Text varchar(8000), #PrevCase varchar, #ModPrefix varchar(10);
DECLARE #FileDataTable TABLE(TableName varchar(200))
INSERT INTO #FileDataTable
select name FROM sys.tables where object_name(object_id) not like 'sys%' order by name
SET #ModPrefix = 'Pur'
DECLARE crsTablesTruncIns CURSOR
FOR select TableName FROM #FileDataTable
OPEN crsTablesTruncIns
FETCH NEXT FROM crsTablesTruncIns INTO #Text
WHILE ##FETCH_STATUS = 0
BEGIN
SET #RetVal = '';
select #i=1, #Ret = '';
while (#i <= len(#Text))
begin
SET #c = substring(#Text,#i,1)
--SET #Ret = #Ret + case when #Reset=1 then UPPER(#c) else LOWER(#c)
IF(#PrevCase = '_' OR #i = 1)
SET #Ret = UPPER(#c)
ELSE
SET #Ret = LOWER(#c)
--#Reset = case when #c like '[a-zA-Z]' then 0 else 1 end,
if(#c like '[a-zA-Z]')
SET #RetVal = #RetVal + #Ret
if(#c = '_')
SET #PrevCase = '_'
else
SET #PrevCase = ''
SET #i = #i +1
end
SET #RetVal = #ModPrefix + #RetVal
print cast(#count as varchar) + ' ' + #RetVal
SET #count = #count + 1
EXEC sp_RENAME #Text , #RetVal
SET #RetVal = ''
FETCH NEXT FROM crsTablesTruncIns INTO #Text
END
CLOSE crsTablesTruncIns
DEALLOCATE crsTablesTruncIns

Answer 5

I'd like to show you my nice and simple solution. It uses Tally function to split the string by pattern, in our case by underscope. For understanding Tally functions, read this article.
So, this is how my tally function looks like:
CREATE FUNCTION [dbo].[tvf_xt_tally_split](
#String NVARCHAR(max)
,#Delim CHAR(1))
RETURNS TABLE
as
return
(
WITH Tally AS (SELECT top (select isnull(LEN(#String),100)) n = ROW_NUMBER() OVER(ORDER BY [name]) from master.dbo.syscolumns)
(
SELECT LTRIM(RTRIM(SUBSTRING(#Delim + #String + #Delim,N+1,CHARINDEX(#Delim,#Delim + #String + #Delim,N+1)-N-1))) Value, N as Ix
FROM Tally
WHERE N < LEN(#Delim + #String + #Delim)
AND SUBSTRING(#Delim + #String + #Delim,N,1) = #Delim
)
)
This function returns a table, where each row represents part of string between #Delim (in our case between underscopes). Rest of the work is simple, just cobination of LEFT, RIGHT, LEN, UPPER and LOWER functions.
declare #string varchar(max)
set #string = ' HRM_APPLICATION_DELAY_IN'
-- convert to lower case
set #string = LOWER(#string)
declare #output varchar(max)
-- build string
select #output = coalesce(#output + '_','') +
UPPER(left(Value,1)) + RIGHT(Value, LEN(Value) - 1)
from dbo.tvf_xt_tally_split(#string, '_')
-- lower first char
select left(lower(#output),1) + RIGHT(#output, LEN(#output) - 1)