如何在没有子查询的情况下从两个表中获取计数

Question

i have two tables,

department  
———-  
deptid (type: INT)  
deptname (type: TEXT)  
hours (type: INT)  
active (type: BIT)  

employee  
——–  
empid (type: INT)  
empname (type: TEXT)  
deptid (type: INT)  
designation (type: TEXT)  
salary (type: INT)  

now how to make query without using subquery that returns the columns empname and deptname of the employees belonging to those departments that have a head count of 4 or more. The records should be returned in alphabetical order of empname.

Answer 1

因为您具有汇总条件 （头数为4或更多），这意味着没有子查询，您将无法获得empname而只能获取deptname 。

Answer 2

Select E.empName, D.DeptName, count(E2.EmpID)
FROM Department D
LEFT JOIN Employee E
  ON E.DeptID = D.DeptID
LEFT JOIN Employee E2
  ON E.DeptID = D.DeptID
GROUP BY E.EmpName, D.DeptName
Having count(e2.empID) >=4

Answer 3

I haven't tested it, but this looks right to me

SELECT empname, deptname, department.deptid
FROM employee JOIN department ON employee.deptid = department.deptid
GROUP BY department.deptid
HAVING count(department.deptid) >= 4
ORDER BY empname;