SQL - Replace non numeric characters in string - sql

Question

I'm writing a function that takes a string and has to replace any non-numeric character with two numeric characters taken from a table. This is the code I use to explore the string and find the non-numeric characters:
SET #string = '1a2b3c4d'
SET #wcount= 0
SET #index = 1
SET #len= LEN(#string)
WHILE #index<= #len
BEGIN
SET #char = SUBSTRING(#string, #index, 1)
IF #char LIKE '%[a-z]%'
PRINT 'char ' + CONVERT(varchar(10), #index)
ELSE
PRINT #char
SET #index= #index+ 1
END
The output is the following
1
char 2
2
char 4
3
char 6
4
char 8
Now, when I find a non-numeric character I have to replace it with two numeric chars taken from a table by a select. E.g.
SELECT #temp = REPLACEMENT FROM Conversion_Tab WHERE EXPR = #char
In conclusion, if I have the following string '1a2a3a4a' and the replacement for 'a' is '88' the resulting string should be '188288388488'
Thanks in advance for any help.
Bye!

Answer 1

Try this
DECLARE #string VARCHAR(100)
DECLARE #outstring VARCHAR(100)
DECLARE #wcount INT
DECLARE #temp INT
DECLARE #index INT
DECLARE #len INT
DECLARE #char CHAR
SET #string = '1a2a3a4a'
SET #wcount= 0
SET #index = 1
SET #len= LEN(#string)
SET #outstring = ''
WHILE #index<= #len
BEGIN
SET #char = SUBSTRING(#string, #index, 1)
IF #char LIKE '%[a-z]%'
BEGIN
SELECT #temp = REPLACEMENT FROM #Conversion_Tab WHERE EXPR = #char
SET #outstring = #outstring + CONVERT(VARCHAR(10),#temp)
END
ELSE
BEGIN
SET #outstring = #outstring + #char
END
SET #index= #index+ 1
END
SELECT #outstring
SQL FIDDLE DEMO

Answer 2

looks like you need isnumeric(). so if not isnumeric(char) replace it with your lookup value.
taken from the other answer but produces the same result
DECLARE #string VARCHAR(100)
DECLARE #outstring VARCHAR(100)
DECLARE #wcount INT
DECLARE #temp INT
DECLARE #index INT
DECLARE #len INT
DECLARE #char CHAR
SET #string = '1a2a3a4a'
SET #wcount= 0
SET #index = 1
SET #len= LEN(#string)
SET #outstring = ''
WHILE #index<= #len
BEGIN
SET #char = SUBSTRING(#string, #index, 1)
IF ISNUMERIC(#char) = 0
BEGIN
SELECT #temp = REPLACEMENT FROM #Conversion_Tab WHERE EXPR = #char
SET #outstring = #outstring + CONVERT(VARCHAR(10),#temp)
END
ELSE
BEGIN
SET #outstring = #outstring + #char
END
SET #index= #index+ 1
END