Need Help with instr/Regexp for the query

Question

Hi Oracle Folks
I am using Oracle
Oracle Database 11g Enterprise Edition Release 11.1.0.7.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options
I have some student responses and the valid values are +/-/O(alphabet)/P and spaces at the end of the sting only not in the middle.
As per my requirement the record number 2 3,4 should be listed from the query but I am getting only one (record 3).
Can we use REG_EXP
Please help.
Thanks in advance.
Rajesh
with x as (
SELECT '+-+-POPPPPPP   ' STUDENT_RESPONSE, 1 record_number FROM DUAL union all
SELECT '+--AOPPPPPP++' STUDENT_RESPONSE, 2 record_number FROM DUAL union all
SELECT '+-+-  OPPPPPP--' STUDENT_RESPONSE, 3 record_number FROM DUAL union all
SELECT '+-+-9OPPPPPP   ' STUDENT_RESPONSE, 4 record_number FROM DUAL )
(SELECT RECORD_NUMBER,
TRIM(STUDENT_RESPONSE) FROM X
WHERE
((INSTR (UPPER(TRIM(STUDENT_RESPONSE)),'-') =0)
OR (INSTR (UPPER(TRIM(STUDENT_RESPONSE)),'+') =0)
OR (INSTR (UPPER(TRIM(STUDENT_RESPONSE)),'O') =0)
OR (INSTR (UPPER(TRIM(STUDENT_RESPONSE)),'P') =0)
OR (INSTR (UPPER(TRIM(STUDENT_RESPONSE)),' ') !=0)
)

Answer 1

Hi, Rajesh,
Rb2000rb65 wrote:
Hi Oracle Folks
I am using Oracle
Oracle Database 11g Enterprise Edition Release 11.1.0.7.0 - 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing optionsThanks for posting this (and the WITH clause for the sample data). That's very helpful.
I have some student responses and the valid values are +/-/O(alphabet)/P and spaces at the end of the sting only not in the middle.Are you combining the responses to several qeustions in one VARCHAR2 column? It might be better to have a separate row for each question.
As per my requirement the record number 2 3,4 should be listed from the query but I am getting only one (record 3). What exactly is your requirement? Are you trying to find the rows where student_response contains any of the forbidden characters, or where it contains a space anywhere but at the end of the string?
Can we use REG_EXPYes, but it's easy enough, and probably more efficient, to not use regular expressions in this case:
Here's one way:
SELECT     record_number
,     student_response
FROM     x
WHERE     TRANSLATE ( UPPER ( RTRIM (student_response, ' '))
            , 'X+-OP'
            , 'X'
            )     IS NOT NULL
;That is, once you remove trailing spaces and all occurrences of '+', '-', 'O' or 'P', then only the forbidden characters are left, and you want to select the row if there are any of those.
If you really, really want to use a regular expression:
SELECT     record_number
,     student_response
FROM     x
WHERE     REGEXP_LIKE ( RTRIM (student_response)
              , '[^-+OP]'          -- or '[^+OP-]', but not '[^+-OP]'.  Discuss amongst yourselves
              , 'i'
;but, I repeat, this will probably be slower than the first solution, using TRANSLATE.
Edited by: Frank Kulash on Oct 17, 2011 1:05 PM
Edited by: Frank Kulash on Oct 17, 2011 1:41 PM
The following is slightly simpler than TRANSLATE:
SELECT     record_number
,     student_response
FROM     x
WHERE     RTRIM ( UPPER ( RTRIM (student_response, ' '))
           , '+-OP'
           )          IS NOT NULL
;