def mk_flatten_mapping(db, into, cols, preserve=[], as_items=False):

    '''Creates a mapping from original column names (which may have collisions)

    This is meant to be used for several tables that are being joined together.

    @param preserve [sql_gen.Col...] Columns not to rename. Note that these

        columns will be included in the mapping even if they are not in cols.

        The tables of the provided Col objects will be changed to into, so make

        * All mappings use the into table so its name can easily be

          changed for all columns at once

    '''

    items = []

    for col in preserve:

        orig_col = copy.copy(col)