MISSING FIELD VALUES ARE NULL

The effect of MISSING FIELD VALUES ARE NULL depends on whether POSITION is used to explicitly state field positions:

• The default behavior is that if field position is not explicitly stated and there is not enough data in a record for all fields, then the record is rejected. You can override this behavior by using MISSING FIELD VALUES ARE NULL to define as NULL any fields for which there is no data available.

• If field position is explicitly stated, then fields for which there are no values are always defined as NULL, regardless of whether MISSING FIELD VALUES ARE NULL is used.

In the following example, the second record is stored with a NULL set for the year_of_birth column, even though the data for the year of birth is missing from the data file. If the MISSING FIELD VALUES ARE NULL clause were omitted from the access parameters, then the second row would be rejected because it did not have a value for the year_of_birth column. The example is followed by a sample of the data file that can be used to load it.

CREATE TABLE emp_load (first_name CHAR(15), last_name CHAR(20), year_of_birth INT)
  ORGANIZATION EXTERNAL (TYPE ORACLE_LOADER DEFAULT DIRECTORY ext_tab_dir
                         ACCESS PARAMETERS (FIELDS TERMINATED BY ","
                                            MISSING FIELD VALUES ARE NULL)
                         LOCATION ('info.dat'));
 
Alvin,Tolliver,1976
Baer,Kenneth
Mary,Dube,1973