SQL: Only Rounded numbers shown, everything else: Useless -

i'm having terrible problems sql, trying calculate values, similiar ex. below:

select sum(ordersachieved)/ sum(saleopportunities) calculatedvalue (         select count(ot.salesopportunity) saleopportunities                count(vk.orders) ordersachieved         fact_vertriebkalkulation vk      ) 

sadly every number takes place in calculation, shown last rounded number! say: 3/4 gives me 0, , 4/4 = 1, 8/4 = 2, , on. while trying find out problem be, found following seems same thing!

select 2/7 value 

gives out = 0!!! tried this

select convert(float,2/7)  value 

and it's same thing! can do, has ever seen this? or know answer question? lot in advance

select 2/7 value 

...using 2 integers means integer division, correct 0.

select 2.0/7 value 

...using @ least 1 floating point type gives 0.285714 seem looking for.

in other words, cast either of operands float, , division give result want;

select convert(float,2)/7  value 

if cast after division done integer division, you'll casting resulting 0.