Spark SQL -连接两个表:如何引用列名？

import org.apache.spark.sql.SparkSession

val spark = SparkSession.builder()
  .appName("Spark SQL Join")
  .config("spark.some.config.option", "some-value")
  .getOrCreate()

// 创建两个DataFrame
val df1 = spark.read.format("csv").option("header", "true").load("table1.csv")
val df2 = spark.read.format("csv").option("header", "true").load("table2.csv")

// 使用表别名
val result1 = df1.alias("t1").join(df2.alias("t2"), $"t1.column1" === $"t2.column2", "inner")
result1.show()

// 使用表名加上列名
val result2 = df1.join(df2, df1("column1") === df2("column2"), "inner")
result2.show()