How to use variable value in select query in hive - hive

Question

I am finding number of days in a month as below.
set ndays=datediff(CONCAT(y, '-', (m + 1), '-', '01'), CONCAT(y, '-', m, '-', '01')) FROM (SELECT month(current_date) as m, year(current_date) as y, day(current_date)) tabl1;
I am checking the value.
select ${hiveconf:ndays}; --O/P 31
I am using this variable in a query and getting error.
select
sum(price)/ ${hiveconf:ndays}
from sales_aly
GROUP BY sales_month;
FAILED: ParseException line 3:0 missing EOF at 'from' near 'tabl1'
Please help me.
Thanks in Advance.

Answer 1

set command will not calculate value of this expression: datediff(CONCAT(y, '-', (m + 1), '-', '01'), CONCAT(y, '-', m, '-', '01')) FROM (SELECT month(current_date) as m, year(current_date) as y, day(current_date)) tabl1 but assigns expression itself as a value. Then when you use variable in the code, expression is substituted instead of variable.
You can calculate your expression in shell and pass it to hive like this:
var=$(hive -e "set hive.cli.print.header=false; select datediff(CONCAT(y, '-', (m + 1), '-', '01'), CONCAT(y, '-', m, '-', '01')) FROM (SELECT month(current_date) as m, year(current_date) as y, from tab1 limit 1) tabl1;")
# Then call your script:
hive -hiveconf ndays=$var -f your_script_file_name
Address variable inside your script: ${hiveconf:ndays}
Alternatively you can use macro. See this: http://svn.apache.org/repos/asf/hive/trunk/ql/src/test/queries/clientpositive/macro.q