Oracle Database Discussions

hi i am trying to load data into a table in my warehouse and while doing so i am trying to set a nefault value for all blank fields. i am using the following command file

LOAD DATA
INFILE 'C:\APP\PENDO\ORADATA\TEST\dissertation.txt' "STR '\r\n'"
APPEND
INTO TABLE PENDO19.SSCUSTOMER1
FIELDS TERMINATED BY ',' OPTIONALLY ENCLOSED BY '"'
TRAILING NULLCOLS
(
CUSTID1 CHAR NULLIF (CUSTID1 = "unknown"),
CUSTNAME1 CHAR NULLIF (CUSTNAME1 = "unknown") ,
CUSTPHONE1 CHAR NULLIF (CUSTPHONE1 = "unknown"),
CUSTSTREET1 CHAR NULLIF (CUSTSTREET1 = "unknown"),
CUSTCITY1 CHAR NULLIF (CUSTCITY1 = "unknown"),
CUSTSTATE1 CHAR NULLIF (CUSTSTATE1 = "unknown"),
CUSTZIP1 CHAR NULLIF (CUSTZIP1 = "unknown"),
CUSTNATION1 CHAR NULLIF (CUSTNATION1 = "unknown")
)

the data is successfully loaded into the warehouse but without any transformation of null values.

Can anyone help me please

Thanks in advance