SQL Loader Concept in oracle

SQL Loader is utility to load external text file into oracle database ;
it has 3 files;
1.control file
2.data file
3.log file;

example
data file look like "Salary.txt"

1,2,3,4
11,22,sd,44
22,33,44,55

control file look like "Salary.CTL"

LOAD DATA
INFILE 'C:\SALARY.TXT'
INTO TABLE TEST1
FIELDS TERMINATED BY ','
(A CHAR,
B CHAR,
C CHAR,
D CHAR
)

AFTER THAT FIRE THE COMMAND

sqlldr user_name/pass@connect_string control=c:\salary.txt log=c:\salary.log