oracle select aplhanumeric value from the column - oracle

Question

In oracle I have a table teststring and column name is STRINGVALUE and values in the column are :
A1CC
A2BB
C1DD
C2CC
ABA28
1B333
AB345
1A222
2NDDD
I have to select only those value which has first 2 values alphanumeric like A1CC,A2BB,1B33,2NDDD etc

Answer 1

SELECT stringvalue FROM teststring
WHERE regexp_like(substr(stringvalue,1,2),'[A-Z][0-9]|[0-9][A-Z]');
or
SELECT stringvalue FROM teststring
WHERE regexp_like(substr(stringvalue,1,2),'[[:alpha:]][[:digit:]]|[[:digit:]][[:alpha:]]');

Answer 2

select only those value which has first 2 values alphanumeric
Your example output doesn't satisfy the rule you mentioned. According to your rule, this is the test case :
SQL> WITH DATA AS(
2 SELECT 'A1CC' STR FROM DUAL UNION ALL
3 SELECT 'A2BB' STR FROM DUAL UNION ALL
4 SELECT 'C1DD' str from dual union all
5 SELECT 'C2CC' STR FROM DUAL UNION ALL
6 SELECT 'ABA28' str from dual union all
7 SELECT '1B333' STR FROM DUAL UNION ALL
8 SELECT 'AB345' STR FROM DUAL UNION ALL
9 SELECT '1A222' STR FROM DUAL UNION ALL
10 SELECT '2NDDD' FROM DUAL)
11 SELECT STR
12 FROM DATA
13 WHERE (REGEXP_LIKE(SUBSTR(STR,1,1),'[[:alpha:]]')
14 AND REGEXP_LIKE(SUBSTR(STR,2,1),'[[:digit:]]'))
15 OR (REGEXP_LIKE(SUBSTR(STR,1,1),'[[:digit:]]')
16 AND REGEXP_LIKE(SUBSTR(STR,2,1),'[[:alpha:]]'))
17 /
STR
-----
A1CC
A2BB
C1DD
C2CC
1B333
1A222
2NDDD
7 rows selected.
SQL>

Answer 3

Thanks Lalit, when i was using regular expression i was missing the keyword digit thats why i was unable to get the right result set.
in my requirement i have more than thousand value in that column so simply i have called the calum name from the table instead of using the dual union and its working fine..
the new query where any number of record available in the column below format would be feasible.
WITH DATA AS(SELECT STRINGVALUE as STR FROM TESTSTRING )
SELECT STR
FROM DATA
WHERE (REGEXP_LIKE(SUBSTR(STR,1,1),'[[:alpha:]]')
AND REGEXP_LIKE(SUBSTR(STR,2,1),'[[:digit:]]'))
OR (REGEXP_LIKE(SUBSTR(STR,1,1),'[[:digit:]]')
AND REGEXP_LIKE(SUBSTR(STR,2,1),'[[:alpha:]]'))

Answer 4

Use this Query
with TAB(TXT) as(
select 'A1CC' from dual union all
select 'A2BB' from dual union all
select 'C1DD' from dual union all
select 'C2CC' from dual union all
select 'ABA28' from dual union all
select '1B333' from dual union all
select 'AB345' from dual union all
select '1A222' from dual union all
select '2NDDD' from dual)
----------------
--- End of Data
----------------
select txt
from tab
where (regexp_like(TXT, '^((\w\d)|(\d\w)){1}\w+'));
To get output like:
| TXT |
|-------|
| A1CC |
| A2BB |
| C1DD |
| C2CC |
| 1B333 |
| 1A222 |
| 2NDDD |