verb-uncount.md
In dbplyr: A 'dplyr' Back End for Databases

symbols weights are dropped in output

Code
  dbplyr_uncount(df, w) %>% show_query()
Output
  <SQL>
  SELECT `x`
  FROM `test`
  INNER JOIN (
    SELECT CAST(`..dbplyr_row_id` AS INTEGER) AS `..dbplyr_row_id`
    FROM (
      SELECT NULL AS `..dbplyr_row_id`
      WHERE (0 = 1)

      UNION ALL

      VALUES (1)
    ) AS `values_table`
  ) AS `RHS`
    ON (`RHS`.`..dbplyr_row_id` <= `test`.`w`)

Code
  df %>% mutate(w = w + 1) %>% dbplyr_uncount(w) %>% show_query()
Output
  <SQL>
  SELECT `x`
  FROM (
    SELECT `x`, `w` + 1.0 AS `w`
    FROM `test`
  ) AS `LHS`
  INNER JOIN (
    SELECT CAST(`..dbplyr_row_id` AS INTEGER) AS `..dbplyr_row_id`
    FROM (
      SELECT NULL AS `..dbplyr_row_id`
      WHERE (0 = 1)

      UNION ALL

      VALUES (1), (2)
    ) AS `values_table`
  ) AS `RHS`
    ON (`RHS`.`..dbplyr_row_id` <= `LHS`.`w`)