我很好奇,我该如何以Spark Dataframe方式实现sql类似于exist子句。
LEFT SEMI JOIN
等效于Spark中的EXISTS
功能。 val cityDF= Seq(("Delhi","India"),("Kolkata","India"),("Mumbai","India"),("Nairobi","Kenya"),("Colombo","Srilanka")).toDF("City","Country")
val CodeDF= Seq(("011","Delhi"),("022","Mumbai"),("033","Kolkata"),("044","Chennai")).toDF("Code","City")
val finalDF= cityDF.join(CodeDF, cityDF("City") === CodeDF("City"), "left_semi")