please tell me what is the query?

Please see the below query . 

SELECT de.CompId,c.Name
,COUNT(de.deptId) AS TotalDept,COUNT(de.empId) AS TotalEmp
      ,MAX(CONVERT(INT, e.Salary)) AS MaxSalary
FROM DeptEmp AS de
   INNER JOIN Companies AS c ON de.CompId = c.CompId
   INNER JOIN Departments AS d ON de.DeptId = d.DeptId
   INNER JOIN Employees AS e ON de.EmpId = e.compId
GROUP BY de.CompId,c.Name,de.deptId,de.empId