如何使用 Java 在 Spark SQL 中加入多列以在 DataFrame 中进行过滤
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How to Join Multiple Columns in Spark SQL using Java for filtering in DataFrame
提问by Gokul
DataFrame a= contains column x,y,z,kDataFrame b= contains column x,y,aa.join(b,<condition to use in java to use x,y >) ???
DataFrame a= 包含列 x,y,z,kDataFrame b= 包含列 x,y,aa.join(b,<condition to use in java to use x,y >) ???
I tried using
我尝试使用
a.join(b,a.col("x").equalTo(b.col("x")) && a.col("y").equalTo(b.col("y"),"inner")
But Java is throwing error saying &&is not allowed.
但是Java抛出错误说&&不允许。
回答by zero323
Spark SQL provides a group of methods on Columnmarked as java_expr_opswhich are designed for Java interoperability. It includes and(see also or) method which can be used here:
Spark SQL 提供了一组Column标记为的方法，java_expr_ops这些方法是为 Java 互操作性而设计的。它包括and（另见or）方法，可在此处使用：
a.col("x").equalTo(b.col("x")).and(a.col("y").equalTo(b.col("y"))
