When I use DataFrame groupby like this:
df.groupBy(df("age")).agg(Map("id"->"count"))
I will only get a DataFrame with columns "age" and "count(id)",but in df,there are many other columns like "name".
In all,I want to get the result as in MySQL,
"select name,age,count(id) from df group by age"
What should I do when use groupby in Spark?