SQL Server : how to remove consecutive duplicate words in a string - sql-server

Question

Currently I have a dynamic query, generated in the stored procedure, that has a bug. Somehow there is a consecutive duplicate 'AND' generated in it.
Wondering if there is a way to delete the CONSECUTIVE DUPLICATE 'AND' from the dynamic query string.
For eg:
var str = 'Select * from employee A where A.age > 30 AND AND A.role = ''developer'''
Update
The replace as suggested below doesnt work
Please see the below query:
DECLARE
#str NVARCHAR(MAX)
SET #str = 'fasdf asdfasf asfasdfasafsdf AND AND asdfasdfasd AND dfasdfa'
SET #str = REPLACE(#str, 'AND AND', 'AND')
PRINT #str
Thanks!

Answer 1

Something like this?
/****** Object: StoredProcedure [dbo].[RemoveConsecutiveDuplicateTokens] Script Date: 30/06/2016 09:30:50 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
CREATE procedure [dbo].[RemoveConsecutiveDuplicateTokens]
#instr varchar(max) ,
#outstr varchar(max) OUTPUT
as
declare #workstr varchar(max) = ltrim(#instr),
#newstr varchar(max),
#oldtoken varchar(max),
#newtoken varchar(max)
while #workstr is not null
begin
if #oldtoken is null
begin
set #oldtoken = SUBSTRING(#workstr,1,charindex(' ',#workstr))
set #workstr = ltrim(Stuff(#workstr, CharIndex(#oldtoken,#workstr), Len(#oldtoken), ''))
set #newstr = #oldtoken + ' '
end
set #newtoken = SUBSTRING(#workstr,1,charindex(' ',#workstr))
if #newtoken <> #oldtoken
begin
if #newtoken <> char(39)
begin
set #oldtoken = #newtoken
set #newstr = #newstr + #newtoken + ' '
set #workstr = ltrim(Stuff(#workstr, CharIndex(#newtoken,#workstr), Len(#newtoken), ''))
end
end
else
begin
set #workstr = ltrim(Stuff(#workstr, CharIndex(#newtoken,#workstr), Len(#newtoken), ''))
end
if charindex(' ',#workstr) = 0
break
end
set #newtoken = SUBSTRING(#workstr,1,len(#workstr))
if #newtoken <> #oldtoken
begin
if #newtoken <> char(39)
begin
set #oldtoken = #newtoken
set #newstr = #newstr + #newtoken + ' '
set #workstr = ltrim(Stuff(#workstr, CharIndex(#newtoken,#workstr), Len(#newtoken), ''))
end
end
else
begin
set #workstr = ltrim(Stuff(#workstr, CharIndex(#newtoken,#workstr), Len(#newtoken), ''))
end
select #outstr = #newstr
return

Answer 2

First of all, you are doing it wrong. Fix the logic that generates this incorrect sql.
But for research/learning purposes, this is how you do.
REPLACE ( str , 'AND AND' , 'AND')

Answer 3

I forgot how much I dislike SUBSTRING, but then that has been my struggle to read <starting_position> as truly the position the value begins with.
However, the real beast was how string manipulations are implemented in SQL Server under the context of the ##TRANCOUNT.
Consider the statement
PRINT QUOTE_NAME(REPLACE('My____Table', '__', '_'))
We wish to use proper naming standards, but the function returns:
`[My__Table]`
Why? Because REPLACE jumps ahead the length of the duplicates. To prove it, lets add one more '_' CHAR(95) and we get this in return:
`[My___Table]`
So then simply embedding this with a WHILE statement, for example, will be quite sufficient for our needs. Note I replaced the spaces with '_' for readability
DECLARE #instr varchar(max)
SET #instr = 'SELECT * from employee A where A.age > 30 AND AND A.role = ''developer'''
DECLARE #workstr varchar(max) = REPLACE(LTRIM(#instr), ' ', '_'),
#tokenque VARCHAR(MAX),
#newstr INT = 0,
#token varchar(max),
#flag_break INT = 0
-- removes the extra "spaces"
WHILE CHARINDEX('__', #workstr) <> 0
BEGIN
SET #workstr = REPLACE(#workstr, '__' , '_')
END
SET #tokenque = #workstr
WHILE (CHARINDEX('_', #tokenque) <> 0)
BEGIN
SET #token = SUBSTRING(#tokenque, 1, CHARINDEX('_', #Tokenque) - 1 )
IF #token <> '''' -- (') delimiter skipped
BEGIN
WHILE CHARINDEX(#token + '_' + #token, #workstr) <> 0
BEGIN
SET #workstr = REPLACE(#workstr, #token + '_' + #token, #token)
END
SET #tokenque = SUBSTRING(#tokenque, LEN(#token) + 2, LEN(#tokenque) )
END
ELSE SET #tokenque = SUBSTRING(#tokenque, LEN(#token) + 2, LEN(#tokenque) )
PRINT #tokenque --if you want to see the progression
END
PRINT REPLACE(#workstr, '_', ' ')
RESULT:
'SELECT * from employee A where A.age > 30 AND A.role = 'developer'

Answer 4

use the REPLACE function and replace 'AND AND' by 'AND'. example
SELECT REPLACE('Select * from employee A where A.age > 30 AND AND A.role = ''developer'' ','AND AND','AND');