Replace string without fixed length - sql

Question

I have some data that I'm looking at that has text formatting stored within a NTEXT field.
Happy enough with SQL Replace to remove data of a known length and format, however there are some fields with what looks like colour formatting and I'm trying to find a way to remove these.
An example of the data below, however (if possible) I would like to be able to remove whatever numbers follow the colours in the data but can't see how to introduce a wildcard into the replace statement.
Something like '\red***\green\***\blue***' as per Excel, but this doesn't work in Sql Server.
declare #str varchar(1500) = '\red3\green73\blue125;Jimmy Jazz\red31\green73\blue125;'
select #str,
replace(#str,'\red31\green73\blue125;','')
Any pointers would be gratefully received, thanks in advance.

Answer 1

Based on your sample data it would appear that you only need to remove the numbers in your string you can use patreplace8k or using patextract8K. Note the sample data and examples below:
-- Sample data
DECLARE #strings TABLE(stringId INT IDENTITY, string VARCHAR(100));
INSERT #strings VALUES('DeepPurple1978\yellow2\red009;pink\black3322'),
('red202\yellow5\red009;hotpink2'),('purple999\gray65\violet;blue\yellow381');
--==== Solution #1 Patreplace8k
SELECT
s.stringId,
pr.newString
FROM #strings AS s
CROSS APPLY samd.patReplace8K(s.string,'[0-9]','') AS pr;
--==== Solution #2 PatExtract8k + STRING_AGG (SQL 2017+)
SELECT
s.stringId,
NewString = STRING_AGG(pe.Item,'') WITHIN GROUP (ORDER BY pe.ItemNumber)
FROM #strings AS s
CROSS APPLY samd.patExtract8K(s.string,'[0-9]') AS pe
GROUP BY s.stringId;
--==== Solution #3 PatExtract8k + XML Concatination (Pre SQL 2017\)
SELECT
s.stringId,
NewString =
(
SELECT pe.item+''
FROM #strings AS s2
CROSS APPLY samd.patExtract8K(s2.string,'[0-9]') AS pe
WHERE s.stringId = s2.stringid
ORDER BY pe.itemNumber
FOR XML PATH('')
)
FROM #strings AS s
GROUP BY s.stringId;
Each of these solutions return:
stringId NewString
----------- -------------------------------------
1 DeepPurple\yellow\red;pink\black
2 red\yellow\red;hotpink
3 purple\gray\violet;blue\yellow
The second and third leverage concatenation, the second compatible with SQL Server 2017+ the third works with earlier versions (you did not include what version you are on.)
To only strip the numbers that follow one or more pre-defined colors you could use patternsplitCM. Note the use of a table with a group of colors your are seeking; in the real world I'd use a real table.
-- Colors
DECLARE #colors TABLE(color VARCHAR(20) PRIMARY KEY);
INSERT #colors VALUES('red'),('green'),('blue'),('yellow'),('purple'),('grey');
-- Sample data
DECLARE #strings TABLE(stringId INT IDENTITY, string VARCHAR(100));
INSERT #strings VALUES('Burger1978\yellow2\red009;pink\86thisfool'),
('red202\yellow5\red009;Freddy99'),('green999\grey65\violet;blue\yellow381');
SELECT
s.stringId, s.string, NewString =
(
SELECT
(
SELECT SUBSTRING(f.Item, IIF(f.M=0 AND EXISTS (SELECT c.Color FROM #colors AS c
WHERE c.Color = f.L),NULLIF(PATINDEX('%[^0-9]',f.item),0),1),8000)
FROM
(
SELECT ps.ItemNumber, ps.Item, ps.[Matched],
LAG(ps.Item,1,ps.Item) OVER (ORDER BY ps.ItemNumber)
FROM dbo.PatternSplitCM(s.string,'[^0-9\ ;]') AS ps
) AS f(ItemNumber,Item,M,L)
ORDER BY f.ItemNumber
FOR XML PATH(''), TYPE
).value('(text())[1]','varchar(8000)')
)
FROM #strings AS s;
Returns:
stringId string NewString
----------- --------------------------------------------- ----------------------------------------
1 Burger1978\yellow2\red009;pink\86thisfool Burger1978\yellow\red;pink\86thisfool
2 red202\yellow5\red009;Freddy99 red\yellow\red;Freddy99
3 green999\grey65\violet;blue\yellow381 green\grey\violet;blue\yellow