你可以用 when 函数来检查 col_1 或者 col_2 为空或 col_3 与允许/不允许的值不同，然后在列中输入：

val df1 = df.withColumn(
    "issue",
    when(
      $"col_1".isNull || $"col_2".isNull || !$"col_3".isin("Allowed", "Not-Allowed"),
      concat_ws(
        ",",
        coalesce($"col_1", lit("")),
        coalesce($"col_2", lit("")),
        $"col_3"
      )
    )
  ).withColumn(
    "col_3",
    when(!$"col_3".isin("Allowed", "Not-Allowed"), "Not-Allowed").otherwise($"col_3")
  )

df1.show
//+-----+------+-----------+------------------+
//|col_1| col_2|      col_3|             issue|
//+-----+------+-----------+------------------+
//|  abc|   123|    Allowed|              null|
//|dasdj|  null|Not-Allowed|dasdj,,Not-Allowed|
//|  dce|   786|Not-Allowed|     dce,786,wrong|
//| null| 23456|Not-Allowed|,23456,Not-Allowed|
//|  def|682364|Not-Allowed|   def,682364,temp|
//|  bcr|   786|Not-Allowed|              null|
//+-----+------+-----------+------------------+

更新列的步骤 col_3 使用默认值 Not-Allowed ，则使用与 when 功能。