I missed this too. However, I've found you can work around it pretty easily with clauses like CASE WHEN @field != "" THEN column = @field ELSE true END.

Example from the sqlc creator (https://github.com/sqlc-dev/sqlc/discussions/364#discussionc...):

  -- name: FilterFoo :many
  SELECT * FROM foo
  WHERE fk = @fk
    AND (CASE WHEN @is_bar::bool THEN bar = @bar ELSE TRUE END)
    AND (CASE WHEN @lk_bar::bool THEN bar LIKE @bar ELSE TRUE END)
    AND (CASE WHEN @is_baz::bool THEN baz = @baz ELSE TRUE END)
    AND (CASE WHEN @lk_baz::bool THEN baz LIKE @baz ELSE TRUE END)
  ORDER BY
    CASE WHEN @bar_asc::bool THEN bar END asc,
    CASE WHEN @bar_desc::bool THEN bar END desc,
    CASE WHEN @baz_asc::bool THEN baz END asc,
    CASE WHEN @baz_desc::bool THEN baz END desc;