I'm stuck up with a problem in which i have to find out a number of people available from a particular date to another particular date.The people are employees in an organization who are involved in more than one projects in an organization at any point of time.The availability criteria for an employee is determined by his/her % of utilization which is < 100 at any point of time. As an example suppose an employee is working on 2 projects. First project start date and end date is from 15th january to 31st march. His % utilization is 50.The 2nd project start date and end date is 2nd feb to 31st august.% of utilization is 50. So we have to determine the availability of the employee between 3rd april to 20th august based on the % utilization that is left for him to be allocated to some other project.please help me in formulating a SQL query to achieve this result.