sqlContext.sql(s"""
SELECT
school_name,
name,
age
FROM my_table
""")

val df = sqlContext.sql(s"""
SELECT
school_name,
age
FROM my_table
GROUP BY school_name
""")

df.groupBy("school_name").agg(make_map)

-------------------
school_name | map
------------------
school A | {"michael": 7, "emily": 5}
school B | {"cathy": 10, "shaun": 5}