I have the following SQL that returns the records as I expected:
IF a.USERID=b.USERID AND b.CUSTID=c.CUSTID then return the records. Well what if I wanted to return all the records from
TMOSER.CZCS_USERS a and TMOSER.CZCS_CUSTOMERS c even if there are no records in TMOSER.CZCS_PWR_USER_CUSTID b?

SELECT a.USERID, c.CUSTID, b.DEFAULT_NPC, a.USER_NAME,
a.FIRST_NAME, a.LAST_NAME, a.UPDATE_USERID, a.USER_EMAIL, c.CUSTOMER_NAME,
c.LOGO_PATH, c.NPC, c.ISACTIVE
FROM TMOSER.CZCS_USERS a, TMOSER.CZCS_PWR_USER_CUSTID b, TMOSER.CZCS_CUSTOMERS c
WHERE a.USERID=b.USERID AND b.CUSTID=c.CUSTID

you could outer join the tables to obtain the desited result

heres an example
DEV> select * from tab1;

ID COL1
---------- ----------
1 A
2 BC
3 AB
4 DE
5 FAG

Elapsed: 00:00:00.01

DEV> select * from tab2;

COL1
----------
A
G

Elapsed: 00:00:00.00

DEV> select tab2.* from tab2, tab1
2 where tab2.col1 = tab1.col1;

COL1
----------
A

Elapsed: 00:00:00.00

the above retreived only matching rows but since you need all rows in TAB2 which do not match in TAB1...

DEV> select tab2.* from tab2, tab1
2 where tab2.col1 = tab1.col1(+);

COL1
----------
A
G

Elapsed: 00:00:00.00
DEV>

if you need a 3 table example :-)

DEV> select * from tab3;

ID
----------
1
2
7

Elapsed: 00:00:00.00
DEV> select * from tab1, tab2, tab3
2 where tab1.id = tab3.id(+)
3 and tab1.col1 = tab2.col1(+);

ID COL1 COL1 ID
---------- ---------- ---------- ----------
1 A A 1
3 AB
2 BC 2
4 DE
5 FAG

Elapsed: 00:00:00.01
DEV>

so all records are from tab1 are displayed and corresponding tab2 and tab3 is displayed if matching else left blank