Substitute for Function STUFF (SQL Server) in AWS redshift - amazon-web-services

Question

I have to replace first 3 digits of a column to a fix first 3 digits (123)
Working SQL Server code. (Not working on AWS RedShift)
Code:
Select
Stuff (ColName,1,3,'123')as NewColName
From DataBase.dbo.TableName
eg 1 -Input --- 8010001802000000000209092396---output -1230001802000000000209092396
eg 2 -Input --- 555209092396- --output -123209092396
it should replace the first 3 digits to 123 irrespective of its length.
Please advice anything that is supported in AWS Redshift.
yet trying using substring and repalce.

Answer 1

I see that AWS RedShift was based on an old version of Postgres, and I looked up the SUBSTRING function for you (https://docs.aws.amazon.com/redshift/latest/dg/r_SUBSTRING.html), which is pretty forgiving of its argument values.
In this sample in Transact-SQL, and as documented for RedShift, the third argument of SUBSTRING can be much longer than the actual strings without causing an error. In Transact-SQL, even the second argument is "forgiving" if it starts after the end of the actual string:
;
WITH RawData AS
(SELECT * FROM (VALUES ('8010001802000000000209092396'),
('555209092396'),
('AB')
) AS X(InputString)
)
SELECT InputString, '123' + SUBSTRING(InputString, 4, 1000) AS OutputString
FROM RawData
InputString OutputString
8010001802000000000209092396 1230001802000000000209092396
555209092396 123209092396
AB 123
As it appears that the concatenation operator in Redshift is ||, I think your expression will be very close to:
'123' || SUBSTRING(InputString, 4, 1000)

Answer 2

Got this and it worked
--Using Substring and concat
Select
cast('123'+substring(ColName,4,LEN(ColName)) as numeric (28)) as NewColName
From DataBase.dbo.TableName