scala -如何用concat_ws连接DataFrame的列？

import org.apache.spark.sql.functions._

// 创建一个示例DataFrame
val df = Seq(
  ("John", "Doe"),
  ("Jane", "Smith"),
  ("Mike", "Johnson")
).toDF("first_name", "last_name")

// 使用concat_ws连接first_name和last_name列，并将结果存储在full_name列中
val result = df.withColumn("full_name", concat_ws(" ", $"first_name", $"last_name"))

// 显示结果
result.show()

+----------+---------+-------------+
|first_name|last_name|    full_name|
+----------+---------+-------------+
|      John|      Doe|    John Doe|
|      Jane|    Smith|  Jane Smith|
|      Mike|  Johnson|Mike Johnson|
+----------+---------+-------------+