Experts Round Table Network

I have been trying to manipulate data from a fairly complex database. I am creating a report that is counting a specified field once it has gone through a query and a couple of filters. The SQL statement became too long for the complete calculation. I have now decided the break up the operation and then calculate the final result from these smaller operations. I am however nervous as to the hierarchy between the first set of operations and the final operation which brings them all together. How can i be sure that the initial operations will be completed before the subsequent operation calculates the final answer?