Spark SQL - Select all AND computed columns?

Question

This is a total noob question, sorry for that. In Spark, I can use select as:

df.select("*"); //to select everything
df.select(df.col("colname")[, df.col("colname")]); //to select one or more columns
df.select(df.col("colname"), df.col("colname").plus(1)) //to select a column and a calculated column

But. How can I select all the columns PLUS a calculated one? Obviously select("*", df.col("colname").plus(1)) doesn't work (compilation error). How can this be done under JAVA? Thank you!

Answer 1

只需这样做：

df.select(df.col("*"), df.col("colName").plus(1));

Answer 2

You can use withColumn() method, this will create a new column to the DataFrame.

df.select("*")
  .withColumn("ColName", col("colName").plus(1))

Answer 3

The difference between .select() and .withColumn() methods is that .select() returns only the columns you specify, while .withColumn() returns all the columns of the DataFrame in addition to the one you defined.

You can directly use withColumn :

df.withColumn("ColName", col("colName").plus(1))