SQL*Loader - Explanation and examples
SQL Loader is a utility that allows you to load data of different format into Oracle. These formats
include delimited text file, csv file, etc... There are two important parts to running SQL Loader:
1. the SQL Loader command line
2. the control file

1. SQL Loader command line

   On UNIX:
   sqlldr CONTROL=/db01/DBSTAR/conversion/ctl/sample.ctl, LOG=/db01/DBSTAR/conversion/log/sample.log,USERID=userid/pwd, direct=true, errors=10000
   On NT:
   sqlldr80 CONTROL=m:\db01\DBSTAR\conversion\ctl\sample.ctl LOG=\db01\DBSTAR\conversion\log\sample.log USERID=userid/pwd direct=true errors=10000

   You can specify the data file in the command line. The parameter is called DATA.
   For example:
   sqlldr80 CONTROL=m:\db01\DBSTAR\conversion\ctl\sample.ctl DATA=m:\db01\DBSTAR\conversion\sample.txt LOG=\db01\DBSTAR\conversion\log\sample.log USERID=userid/pwd direct=true errors=10000

   Note specifying the data file in the control file, the parameter is INFILE sample.txt however
   in the sql loader command line, the parameter in DATA sample.txt
   The following is a list of all the parameters that may be used in the command line:
   USERID - Oracle username/password
   CONTROL - Control file name 
   LOG - Log file name 
   BAD - Bad file name
   DATA - Data file name
   DISCARD - Discard file name
   DISCARDMAX - Number of discards to allow (Default all)
   SKIP - Number of logical records to skip (Default 0)
   LOAD - Number of logical records to load (Default all)
   ERRORS - Number of errors to allow (Default 50)
   ROWS - Number of rows in conventional path bind array or between direct path data saves
          (Default: Conventional Path 64, Direct path all)
   BINDSIZE - Size of conventional path bind array in bytes (System-dependent default)
   SILENT - Suppress messages during run (header, feedback, errors, discards, partitions, all)
   DIRECT - Use direct path (Default FALSE)
   PARFILE - Parameter file: name of file that contains parameter specifications
   PARALLEL - Perform parallel load (Default FALSE)
   FILE - File to allocate extents from

2. The control file
   specify -- for comment line
   OPTIONS keyword allows you to specify runtime arguments in the control file rather than 
   in the command line. It always precede the LOAD DATA keyword

   Other parameters that are specified in the control file are:
   RECOVERABLE/UNRECOVERABLE - Loaded data is logged in the redo log if RECOVERABLE. 
      RECOVERABLE is default for direct path loads. All conventional loads are recoverable.
      UNRECOVERABLE can only be specified for DIRECT path and is used to improve performance
   LOAD DATA - command to start loading the data
   INFILE - File to load data from multiple datafiles in one run of SQL*Loader
   Ex:   INFILE  mydat1.dat  BADFILE  mydat1.bad  DISCARDFILE mydat1.dis 
         INFILE  mydat2.dat 

   BADFILE - File for SQL Loader to place records that were rejected because of formatting errors 
      or because they caused Oracle errors.
   DISCARDFILE - File for SQL Loader to place records that do not meet any of the loading criteria
      (does not meet the WHEN criteria)
   INSERT/APPEND/REPLACE/TRUNCATE - command to specify how to laod the data
   The following are examples of a control file:   

   Example 1: Loading fixed length file
      In the database, make sure that the table you are loading the data in exist:
      Sample table: create table sample 
                     (sample_col1 char(1), 
                      sample_col3 char(2));
      Control file, sample.ctl:
         LOAD DATA
         INFILE sample.txt
         INTO TABLE sample
         (sample_col1                    POSITION(01:08) CHAR,
         sample_col2                     POSITION(11:16) DATE "YYMMDD" NULLIF collection_date=BLANKS,
         sample_col3                     POSITION(17:25) DECIMAL EXTERNAL,
         sample_col4                     POSITION(33:67) CHAR)
        SQL Loader command line:
        sqlldr userid=userid/pwd@dbalias control=sample.ctl, log=sample.log

   Example 2: Loading data from a comma delimited file
      In the database, make sure that the table you are loading the data in exist:
      Sample table: 
         create table sample 
         (stats_type varchar2(100),
			STATS_DATE  date  ,
			STATS_NAME  varchar2(100),
			VALUE1      number  ,
			VALUE2      number  ,
			VALUE3      number  ,
			VALUE4      number  ,
			VALUE5      number  ,
      Control file, comma.ctl:
			load data
			infile comma.dat
			into table comma_table
			trailing nullcols
			STATS_DATE    ,
			STATS_NAME    ,
			VALUE1        ,
			VALUE2        ,
			VALUE3        ,
			VALUE4        ,
			VALUE5        ,

      SQL Loader command line:
         sqlldr control=comma.ctl, bad=comma.bad, log=comma.log, userid=userid/pwd@db

For more examples and further explanation, refer to the oracle documentation under utilities.