sql server - How to show '0' amount for a month, if no data exists in the table for that month -

i have 2 tables costtable (id,resourceid, amount,date) , resourcetable (resourceid,name) shows output below.

i want show 0 amount rest of name in case of september. e.g. if rest of resources not appear in cost table should appear 0 in amount

my desired output

my current query

select     rg.id id,     rg.name name,     isnull(sum(ac.amount), 0) amount,     right(convert(varchar(10), ac.[date], 105), 7) [yearmonth]      cost ac     inner join resource rg on ac.resourcegroupid = rg.id      ac.portalid = '100' ,      [date] >= dateadd(month, datediff(month, 0, dateadd(m, -11, getdate())), 0) group      rg.name,      rg.id,      right(convert(varchar(10), ac.[date], 105), 7) order      rg.name desc 

you can cross join , left join. question hard follow because tables , descriptions differ. however, idea:

select t.minid, t.name, ym.yearmonth, coalesce(amount, 0) amount (select name, min(id) minid t group name) n cross join      (select distinct yearmonth t) ym left join      t      on t.name = n.name , t.yearmonth = ym.yearmonth;