Regex to get 00 if the string has less digits - sql

Question

I have a column that is giving me output like 'ABC2001' , 'ABC100145', 'ABC009282' ,' ABC1901'
I want to change this column value to have '00' in between literals and numbers if number is less than 6 digits. Something like -
COL_A
------------
ABC2001
ABC100145
ABC009282
ABC1901
Expected output
COL_B
------------
ABC002001
ABC100145
ABC009282
ABC001901
How to use regex for this ? Currently I am using
SELECT SUBSTR(COL_A,1,3)||LPAD(REGEXP_REPLACE(COL_A,'\D+'),6,'0') FROM TAB
and it is giving me output like -
ABC210073
ABC210073

Answer 1

You do not need (slow) regular expressions and can use simple string functions:
SELECT col_a,
SUBSTR(col_a, 1, 3) || LPAD(SUBSTR(col_a, 4), 6, '0') AS col_b
FROM table_name;
Which, for your sample data:
CREATE TABLE table_name (col_a) AS
SELECT 'ABC2001' FROM DUAL UNION ALL
SELECT 'ABC100145' FROM DUAL UNION ALL
SELECT 'ABC009282' FROM DUAL UNION ALL
SELECT 'ABC1901' FROM DUAL;
Outputs:
COL_A
COL_B
ABC2001
ABC002001
ABC100145
ABC100145
ABC009282
ABC009282
ABC1901
ABC001901
db<>fiddle here

Answer 2

Just for fun, for different prefixes:
usual string functions: trim/lpad/substr:
with table_name (col_a) AS (
SELECT 'ABC2001' FROM DUAL UNION ALL
SELECT 'ABC100145' FROM DUAL UNION ALL
SELECT 'ABC009282' FROM DUAL UNION ALL
SELECT 'ABC1901' FROM DUAL UNION ALL
-- other different prefixes:
select 'ABC2001' from dual union all
select 'AB100145' from dual union all
select 'A-BC9282' from dual union all
select 'A8C2374' from dual union all
select '7x-ABC32129' from dual union all
select '123ABC8942' from dual
)
select v.*, prefix||num as col_b
from (
select
col_a,
rtrim(col_a,'0123456789') as prefix,
lpad(substr(col_a,1+length(rtrim(col_a,'0123456789'))),6,'0') as num
from table_name
) v
;
DBFiddle
using regex functions:
with table_name (col_a) AS (
SELECT 'ABC2001' FROM DUAL UNION ALL
SELECT 'ABC100145' FROM DUAL UNION ALL
SELECT 'ABC009282' FROM DUAL UNION ALL
SELECT 'ABC1901' FROM DUAL UNION ALL
-- other different prefixes:
select 'ABC2001' from dual union all
select 'AB100145' from dual union all
select 'A-BC9282' from dual union all
select 'A8C2374' from dual union all
select '7x-ABC32129' from dual union all
select '123ABC8942' from dual
)
select
col_a,
regexp_replace(
regexp_replace(col_a,'(\d+)$','00000\1')
,'0*(\d{6})$'
,'\1'
) as col_b
from table_name
;
DBFiddle
regex solution for padding numbers to the maximum their length, ie not knowing max numbers length(if it's not hard-coded 6):
select
v.*,
regexp_replace(
regexp_replace(col_a,'(\d+)$',rpad('0',max_num_length,'0')||'\1')
,'0*(\d{'||max_num_length||'})$'
,'\1'
) as col_b
from (
select t.*, max(length(regexp_substr(col_a,'\d+$')))over() as max_num_length
from table_name t
) v
;
DBFiddle