If Columns property consists of some columns they will be deleted before calling CreateColumns() method. TableName property must be set before calling this method.

CreateColumns() retrieves all columns from the table. It means that when inserting the data, SQL INSERT statement is generated for all of the columns, regardless of how many you have assigned with SetValue method. The columns you have omitted are considered to be of NULL value. If you want to generate the statements for chosen columns only, you have to manually edit the collection.

Note: This method is not supported in .NET Standard 1.3 compatible assembly. It is available only in the assembly for full .NET Framework and .NET Standard 2.0 compatible assembly.

Note that "GENERATED ALWAYS AS IDENTITY" columns, introduced in Oracle 12c should not be included in the Columns collection. In the OCI mode, dotConnect for Oracle automatically detects such columns and skips them when creating the Columns collection. In the OracleConnection.Direct mode you should manually delete such columns from the created collection.

Target Platforms: Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

Reference

OracleLoader Class
OracleLoader Members