Hi, I have a question regarding outer joins. Suppose I have the following 2 tables each having 2 columns.
Employee: EmpId, DeptId
Department: DeptId, DeptId
EmpId is primary key in Employee and DeptId is primary key in Department. Also, Employee.DeptId is foreign key referencing Deparment.DeptId.
My first question:
1. Suppose I want all the department ids and the number of employees in them (even if there are 0 employees), is the below query correct:
Select D.DeptId, Count(*) from Department D LEFT OUTER JOIN Employee E ON D.DeptId = E.DeptId GROUPBY D.DeptId;
2. To find all the department ids having 0 employees in them, is the following correct?
Select D.DeptId from Department D LEFT OUTER JOIN Employee E ON D.DeptId = E.DeptId GROUPBY D.DeptId HAVING COUNT(*) = 0;
Thanks for your time.