How to use Hive Query results(multiple) in a variable for other query

Question

I have two tables one is schools and one is students.I want to find all the students of a particular school. The schema of schools is: id, name, location and of students is

Answer 1

Use collect_set() with concat_ws to get comma delimited string, IDs should be cast to string:

schoolId=$(hive -e "set hive.cli.print.header=false;select concat_ws('\\',\\'',collect_set(cast(id as string))) from school;");

hive -hiveconf "schoolId"="$schoolId" 

Then use IN operator:

select id,name from student where schoolId in ('${hiveconf:schoolId}');