Oracle SQL getting the nth element regexp

问题:

I am trying to get the nth element in a comma separated string using SQL in Oracle.

I have the following so far..

SELECT regexp_substr(
   '100016154,5101884LT00001,,,,,100000010892100000012655,L,SEI,5101884LT00001,1,SL,3595.03,00,2,N,N,G,N',
   '[^,]+',
   1,
   7)
FROM dual;

but it doesn't work when the element is empty i.e. ,, can anyone help?

回答1:

If your delimited values are always alphanumeric in between the commas then you could try:

SELECT REGEXP_SUBSTR( <delimied_string>, '[[:alnum:]]{0,},', 1, 7 )
  FROM dual;

To get the seventh value (including the trailing comma). If it is empty you just get the trailing comma (which you can easily remove).

Obviously, if you want a value other than the seventh then change the fourth parameter value to whichever nth occurrance you want e.g.

SELECT REGEXP_SUBSTR( <delimied_string>, '[[:alnum:]]{0,},', 1, <nth occurance> )
  FROM dual;

EDIT: As I love REGEX here is a solution that also removes the trailing comma

SELECT REPLACE(
          REGEXP_SUBSTR(<delimied_string>, '[[:alnum:]]{0,},', 1, <nth>), 
          ','
       )
  FROM dual;

hope it helps

回答2:

You can do it with a little trick: first replacing all commas by a comma followed by a space, and afterwards skip that extra leading space:

SQL> with data as
  2  ( select '100016154,5101884LT00001,,,,,100000010892100000012655,L,SEI,5101884LT00001,1,SL,3595.03,00,2,N,N,G,N' txt
  3      from dual
  4  )
  5  select regexp_substr(txt,'[^,]+',1,7)                             seventh_element_wrong
  6       , replace(txt,',',', ')                                      with_extra_space_after_comma
  7       , regexp_substr(replace(txt,',',', '),'[^,]+',1,7)           seventh_element_leading_space
  8       , substr(regexp_substr(replace(txt,',',', '),'[^,]+',1,7),2) the_seventh_element
  9    from data
 10  /

S WITH_EXTRA_SPACE_AFTER_COMMA
- ----------------------------------------------------------------------------------------------------------------------
SEVENTH_ELEMENT_LEADING_S THE_SEVENTH_ELEMENT
------------------------- ------------------------
1 100016154, 5101884LT00001, , , , , 100000010892100000012655, L, SEI, 5101884LT00001, 1, SL, 3595.03, 00, 2, N, N, G, N
 100000010892100000012655 100000010892100000012655

Regards,
Rob.

回答3:

Unless you're stuck on regular expressions, this works as well:

WITH q AS (
SELECT '100016154,5101884LT00001,,,,,100000010892100000012655,L,SEI,5101884LT00001,1,SL,3595.03,00,2,N,N,G,N' thestring FROM dual
)
SELECT SUBSTR(thestring, INSTR(thestring,',',1,6)+1, 
                         INSTR(thestring,',',1,7)-INSTR(thestring,',',1,6)-1) "The Element"
  FROM q;

The Element
------------------------
100000010892100000012655

Another possibility. You have not specified what the source of your data is. Could you possibly use an external table to read your input source and process it via SQL?

回答4:

SELECT rtrim(regexp_substr('100016154,5101884LT00001,,,,,100000010892100000012655,L,SEI,5101884LT00001,1,SL,3595.03,00,2,N,N,G,N','[^,]{0,}[,]?',1,7),',')
FROM dual;