Column objects in the control file are described in terms of their attributes. If the object type on which the column object is based is declared to be nonfinal, then the column object in the control file may be described in terms of the attributes, both derived and declared, of any subtype derived from the base object type. In the data file, the data corresponding to each of the attributes of a column object is in a data field similar to that corresponding to a simple relational column.
With SQL*Loader support for complex data types such as column objects, the possibility arises that two identical field names could exist in the control file, one corresponding to a column, the other corresponding to a column object's attribute. Certain clauses can refer to fields (for example, WHEN, NULLIF, DEFAULTIF, SID, OID, REF, BFILE, and so on), causing a naming conflict if identically named fields exist in the control file.
Therefore, if you use clauses that refer to fields, then you must specify the full name. For example, if field fld1 is specified to be a COLUMN OBJECT and it contains field fld2, then when you specify fld2 in a clause such as NULLIF, you must use the full field name fld1.fld2.
The following sections show examples of loading column objects: