Pepsi = PEPSI ?!

Question

Hi,
Here's a simplified query that returns results based on two simple conditions:
1) contact's not being null
2) value of col orders.agn equal to col accounts.acnt_name
SELECT o.c_name, o.adv, o.agn,
ac.acnt_name
FROM accounts ac, orders o
WHERE
o.contact_name IS NOT NULL
AND
o.agn = ac.acnt_name
Nothing spectacular...but I get a row that I shouldn't be getting...
There's an accounts.acnt_name = 'Pepsi' and there's an orders.agn = 'PEPSI'.
Oracle is case-sensitive, so how come this happens?

Answer 1

Check your NLS_COMP and NLS_SORT parameters.
SQL> select * from dual where 'pepSi'='PEPSI';
no rows selected
[pre]SQL> alter session set nls_sort=binary_ci;
Session altered.
SQL> alter session set nls_comp=LINGUISTIC;
Session altered.
SQL> select * from dual where 'pepSi'='PEPSI';
D
X
SQL>
Useful links:
Linguistic Comparison Examples
http://download.oracle.com/docs/cd/B19306_01/server.102/b14225/ch5lingsort.htm#sthref644
NLS_COMP
http://download.oracle.com/docs/cd/B19306_01/server.102/b14237/initparams120.htm#sthref508
NLS_SORT
http://download.oracle.com/docs/cd/B19306_01/server.102/b14237/initparams130.htm#sthref554