在oracle中为插入存储过程添加临时列

I am trying to add a temporary column to a target table and use that column in a where clause to insert new data into a parent table via stored procedure that I am using for a one-to-one relationship from parent to target table (see code below). I am getting an error with the alter table add column statement thus resulting in the IMPORT_NUMBER being an invalid identifier. Any help would be much appreciated.I am trying to add a temporary column to a targ