SQL queries to get the duplicate records based on trim I have a table that has got the below set of records.

UNMASK  MASK
123 897609
00123   896509
0000456 5632789
456 32567889
5678    5632789


From the above table I need to select only the below records.

  UNMASK    
123 
00123   
0000456 
456 


(I.E) Whatever values in UNMASK has any number of '0' before the '1-9' and also the row that doesn't have 0s before that 1-9. 

Like 123 and there can be 000000123, 456 and 00456, I need such records(only Prefixed with 0s and the original value) in the output using SQL query in Oracle.

I tried the below query but it doesn't work the way I want.

Select UNMASK,TRIM (LEADING '0' FROM UNMASK) from HSA.TEST_TABLE group by UNMASK having count(TRIM(LEADING '0' FROM UNMASK)) &gt; 1;
Test data: 

create table test_table(unmask varchar(20), mask varchar(20));
insert into test_table values('123', '897609');
insert into test_table values('00123','896509');
insert into test_table values('0000456','5632789');
insert into test_table values('456','32567889');
insert into test_table values('5678','5632789');


I've done this with a CTE, as I love them. casting the string to a number removes the leading characters, which I find easier than messing around with TRIM.

Query:

with duplicates as 
(
  select cast(unmask as number) as unmask_num, count(*) as cnt
  from test_table
  group by cast(unmask as number)
  having count(*)&gt;1
)
select *
from duplicates
join test_table on duplicates.unmask_num = cast(unmask as number)
;


DB Fiddle that demonstrates is here.