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.

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

DbLoader Class
DbLoader Members