Invalid number error when trying to convert a varchar2 to a number.

Question

I need to extract the middle four numbers from a varchar2(12) and then convert it to a number. The middle four are numbers but the first four can have letters. I've tried
TO_NUMBER(substr(wptk.ext_wo_num,5,4))
TO_NUMBER(LPAD(wptk.ext_wo_num,5,4))
substr(TO_NUMBER(wptk.ext_wo_num) ,5,4)
cast as number
I need to get rid of any 0 that are at the beginning of the four numbers. Some of the data has no 0 and some can have up to three 0 at the beginning. Is there a way to do that?
thanks.

Answer 1

user10426897 wrote:
I came back with 56 rows that look like this 1127-0651-E1. I am trying to translate an ingres view into Oracle that has this in the select statement: INT4(LEFT(TRIM(RIGHT(wptk.ext_wo_num,8)),4))You could use regular expressions...
SQL> with t as (select '065101412354' as num from dual union all
  2             select '065106523237' from dual union all
  3             select '065206523238' from dual union all
  4             select '065606542356' from dual union all
  5             select '080101410218' from dual union all
  6             select '080102520218' from dual union all
  7             select '080106020218' from dual union all
  8             select '080201120219' from dual union all
  9             select '080601111214' from dual union all
10             select '080801351216' from dual union all
11             select '080802511216' from dual union all
12             select '10000133013' from dual union all
13             select '10000133SC3' from dual union all
14             select '10000133SP4' from dual union all
15             select '10000211011' from dual union all
16             select '10000241011' from dual union all
17             select '10000601S29' from dual union all
18             select '10000601SC1' from dual union all
19             select '10000601SH2' from dual union all
20             select '10000601SP2' from dual union all
21             select '10000602A11' from dual union all
22             select '10000602A50' from dual union all
23             select '10000602A54' from dual union all
24             select '10000602A59' from dual union all
25             select '10000602C06' from dual union all
26             select '10000602E67' from dual union all
27             select '10000602M00' from dual union all
28             select '10000602M01' from dual union all
29             select '10000602M07' from dual union all
30             select '1127-0651-E1' from dual)
31  --
32  select num, to_number(regexp_replace(num,'^.{4}-?([0-9]{4}).*$','\1')) as num_num
33  from t
34  /
NUM            NUM_NUM
065101412354       141
065106523237       652
065206523238       652
065606542356       654
080101410218       141
080102520218       252
080106020218       602
080201120219       112
080601111214       111
080801351216       135
080802511216       251
10000133013        133
10000133SC3        133
10000133SP4        133
10000211011        211
10000241011        241
10000601S29        601
10000601SC1        601
10000601SH2        601
10000601SP2        601
10000602A11        602
10000602A50        602
10000602A54        602
10000602A59        602
10000602C06        602
10000602E67        602
10000602M00        602
10000602M01        602
10000602M07        602
1127-0651-E1       651
30 rows selected.
SQL>