Thanks again. Where do I put that select statement ? Here is my control file :

options(direct=false)
recoverable
Load Data
Replace into table table_table
FIELDS TERMINATED BY ','
TRAILING NULLCOLS
(DATE_TIME "to_date(substr(ATE_TIME,1,14), 'YYYYMMDDHH24MISS')",
FIRST_FIELD,
SECOND_FIELD,
SEQ_FIELD "mysequence.nextval"
)