insert_in_tables = [insert_in_table]

    conds = set()

    join_cols = sql_gen.ColDict(db, out_table)

    def mk_main_select(joins, cols):

        conds_ = [(sql_gen.with_table(k, insert_in_table), v) for k, v in conds]

        return sql.mk_select(db, joins, cols, conds_, limit=limit_ref[0],

            # Different rows violating different unique constraints not

            # supported

            assert not join_cols

            join_cols.update(util.dict_subset_right_join(mapping, e.cols))

            log_debug('Ignoring existing rows, comparing on these columns:\n'

                +strings.as_inline_table(join_cols, ustr=col_ustr))