Default: The default is that no NULLIF checking is done.
NULLIF parameter specifies a value that is used to determine whether a field is loaded as a NULL column.
Syntax and Description
NULLIF = "string"
NULLIF != "string"
SQL*Loader checks the specified value against the value of the field in the record. If there is a match using the equal (=) or not equal (!=) specification, then the field is set to NULL for that row. Any field that has a length of 0 after blank trimming is also set to NULL.
In the following example, if there are any fields whose value is a period, then those fields are set to NULL in their respective rows.
> sqlldr hr TABLE=employees NULLIF="."