ask for a split function in oracle - sql

Question

right now there is a string like this:
789+456-239
I want to get a list like this:
sign | num
+ 789
+ 456
- 239

Answer 1

This could be a way, by using a commonly used split string method, just adapted to your need to handle the sign.
-- test case
with yourString(str) as
(
select '+789+456-239 ' str
from dual
)
-- query
SELECT regexp_substr(str, '[+-]', 1, level) sign,
regexp_substr(str, '[^+-]+', 1, level) num
FROM ( select case
when substr(str, 1, 1) in ('+','-') then str
-- I add a plus sign if the first char of the string is not a sign
else '+' || str
end as str
from yourString
)
CONNECT BY regexp_instr(str, '[+-]', 1, level ) > 0
This gives:
SIGN NUM
-------------- --------------
+ 789
+ 456
- 239
Here I assume that if no sign is given in the beginning of this string, the first sign will be +.
If you need to handle more than one string, you need to identify an ID in your table and the CONNECT BY becomes a bit more complex:
-- test case
with yourString(id, str) as
(
select 1, '+789+456-239' from dual union all
select 2, '789+456-239' from dual union all
select 3, '-789+456-239' from dual
)
-- query
SELECT id,
regexp_substr(str, '[+-]', 1, level) sign,
regexp_substr(str, '[^+-]+', 1, level) num
FROM ( select id,
case
when substr(str, 1, 1) in ('+','-') then str
-- I add a plus sign if the first char of the string is not a sign
else '+' || str
end as str
from yourString
)
CONNECT BY regexp_instr(str, '[+-]', 1, level ) > 0
and prior id = id
and prior sys_guid() is not null
The result:
ID SIGN NUM
---------- ----- --------------------------------------------
1 + 789
1 + 456
1 - 239
2 + 789
2 + 456
2 - 239
3 - 789
3 + 456
3 - 239

Answer 2

Here is a method that does not use regular expressions and can handle multiple input rows:
SQL Fiddle
Oracle 11g R2 Schema Setup:
CREATE TABLE table_name ( id, list ) AS
SELECT 1, '789+456-239' FROM DUAL UNION ALL
SELECT 2, '-123' FROM DUAL UNION ALL
SELECT 3, '+456' FROM DUAL UNION ALL
SELECT 4, '789' FROM DUAL;
Query 1:
WITH bounds ( id, list, start_pos, end_pos, lvl ) AS (
SELECT id,
list,
1,
CASE
WHEN INSTR( list, '+', 2 ) = 0 THEN INSTR( list, '-', 2 )
WHEN INSTR( list, '-', 2 ) = 0 THEN INSTR( list, '+', 2 )
ELSE LEAST( INSTR( list, '+', 2 ), INSTR( list, '-', 2 ) )
END,
1
FROM table_name
UNION ALL
SELECT id,
list,
end_pos,
CASE
WHEN INSTR( list, '+', end_pos + 1 ) = 0 THEN INSTR( list, '-', end_pos + 1 )
WHEN INSTR( list, '-', end_pos + 1 ) = 0 THEN INSTR( list, '+', end_pos + 1 )
ELSE LEAST( INSTR( list, '+', end_pos + 1 ), INSTR( list, '-', end_pos + 1 ) )
END,
lvl + 1
FROM bounds
WHERE end_pos > 0
)
SELECT id,
DECODE( SUBSTR( list, start_pos, 1 ), '-', '-', '+' ) AS sign,
SUBSTR(
list,
start_pos + DECODE( SUBSTR( list, start_pos, 1 ), '-', 1, '+', 1, 0 ),
DECODE( end_pos, 0, LENGTH( list ) + 1, end_pos ) - start_pos - DECODE( SUBSTR( list, start_pos, 1 ), '-', 1, '+', 1, 0 )
) AS item,
lvl
FROM bounds
ORDER BY id, lvl
Results:
| ID | SIGN | ITEM | LVL |
|----|------|------|-----|
| 1 | + | 789 | 1 |
| 1 | + | 456 | 2 |
| 1 | - | 239 | 3 |
| 2 | - | 123 | 1 |
| 3 | + | 456 | 1 |
| 4 | + | 789 | 1 |