Oracle: remove first 4 characters from a string

Question

So I want to remove the first 4 characters from a string in oracle. Those characters can be different every time. In my case I need to take away the first 4 characters of an IBAN and put them at the end of the string. I got the part of putting them to the end of the string but I can't get the first 4 characters to be removed. Every solution I find on the internet removes specified characters, not characters from a certain position in the string (1 to 4). I used the code below to get the first 4 characters to the end of the string and wanted to try something similar for removing them at the front but without success.

SELECT SUBSTR(iban_nummer, 1, 4) INTO iban_substring FROM dual;
iban_nummer := iban_nummer || iban_substring;

Answer 1

See the docs:

substring_length ... When you do not specify a value for this argument, then the function returns all characters to the end of string. When you specify a value that is less than 1, the function returns NA.

So iban_nummer := substr(iban_nummer, 5) || substr(iban_nummer, 1,4) should work. The first part selects all characters beginning from the 5th, the second character numbers 1..4.

Answer 2

update table_name set col_name=substr(col_name,5);

Answer 3

try regexp, like:

SELECT regexp_replace(t.iban_nummer,'(.{4})(.*)','\2\1') FROM t;