如何在postgresql的选择查询中插入列的总和？

Question

我有一个选择查询，我的列类型是文本，然后我使用查询将其转换为整数

 select case
   when fti.status!='not signed' then  1::integer
   when ftrq.is_the_site_cleared = '1' then 1::integer 
   when ftrq.is_the_site_cleared = '0' then 0::integer
   end as is_the_site_cleared from fti join ftrq on ftrq.fulcrum_parent_id = fti.fulcrum_id

我确实有很多这样的列，并且希望将它们的总数作为列中的最后一个值，这可能类似于底部的 sum(is_the_site_cleared )。我怎样才能做到这一点？我正在使用 postgresql 9.3，它说 sum(text) 函数不存在。请帮忙！！！

Answer 1

    select sum(is_the_site_cleared) from (select case
       when fti.status!='not signed' then  1
       when ftrq.is_the_site_cleared = '1' then 1 
       when ftrq.is_the_site_cleared = '0' then 0
       end as is_the_site_cleared from fti join ftrq on 
       ftrq.fulcrum_parent_id = fti.fulcrum_id) res;