Oracle - REGEXP_SUBSTR前导零被忽略的问题

Question

执行低于查询时我得到“235”而不是预期结果“0”

select  REGEXP_SUBSTR(000.235||'', '[^.]+', 1, 1)  from dual;

Answer 1

Do this instead, and you'll see where the problem comes:

select  000.235||'' from dual

Result:

.235

The regexp picks up the first longest occurrence of non-period, which in this string is "235", so it's working correctly; it's the input value that is broken

Now, if you'd written it like this, it would be fine:

select  REGEXP_SUBSTR('000.235', '[^.]+', 1, 1)  from dual

So why the odd presentation of the numeric? What does your data in your table look like? This is unlikely to be the actual query you're running - if you need help with the true query, post it up

Answer 2

Oracle trim numeric values, you can fix it by adding ltrim to number:

select REGEXP_SUBSTR(ltrim(' 000.235')||'', '[^.]+', 1, 1) from dual;

result: 000 as expected