RETCODE bcp_columns ( HDBC hdbc, INT nColumns);
Is the bulk copy-enabled ODBC connection handle.
Is the total number of columns in the user file. Even if you are preparing to bulk copy data from the user file to an SQL Server table and do not intend to copy all columns in the user file, you must still set nColumns to the total number of user-file columns.
SUCCEED or FAIL.
This function can be called only after bcp_init has been called with a valid file name.
You should call this function only if you intend to use a user-file format that differs from the default. For more information about a description of the default user-file format, see bcp_init.
After calling bcp_columns, you must call bcp_colfmt for each column in the user file to completely define a custom file format.