ApplyColumnMapping

ApplyColumnMapping operation transforms columns of the input table by applying a mapping specified in the mapping table. Although this operation is more general as it allows computing any expression in the tranformation, the main use case is just to rename columns of the input table using name mapping specified in the mapping table (in this use case the expression is just the name of the input column).

Parameters:

• Source, Space, and Table specify the input table.
• Target Source, Target Space, and Target Table specify the target table. The target table contains the result of the mapping application.
• Table vs View defines whether the target table will be created as a permanent table or a view.
• Mapping Table Source, Mapping Table Space, and Mapping Table Table specify the mapping table. Mapping table must include the following columns:
• from_expr - any expression in a language supported by the source (eg SQL). For exmaple, if you want just to rename coloumns, from_expr contains the name of a source column properly quoted if needed because it will be evaluated as an expression).
• to_col_name - name of the result column.
• to_position - integer value that defines a sequential order of the result columns. We sort by to_position column in ascending order to determine the order of the result columns.