Tables that look like bellow
How to write SQL Query to read all department names with an employee count salary > 1000, if a department not found in employee we required to show as zero counts in output.
You can use left join and aggregation:
select d.name, count(e.id)
from departments d left join
employees e
on e.department_id = d.id and e.salary >= 10000
group by d.name
Related
This gets me the number of employees per department
SELECT department, COUNT(idEmployees) empCount
FROM employees
GROUP BY department;
You could join on departments to get the buildingID, and then group by that:
SELECT buildingID, COUNT(*)
FROM employees e
JOIN department d ON e.department = d.departmentID
GROUP BY buildingID
i think this is the solution
select d.buildingID, count(e.ID)
from department d
inner join employees e
on d.departmentID = e.department
group by d.buildingID
This question can be answered in two ways. Firstly, if all employees of a department must be attached in a building. Secondly few employees of a department are attached to a building.
For one where employees are attached to a building it's mandatory
SELECT d.buildingId
, COUNT(e.id) count_employee
FROM departments d
INNER JOIN employees e
ON d.departmentid = e.department
GROUP BY d.buildingId
For second where employees are attached to a building but it's optional. In that case LEFT JOIN is used.
SELECT b.buildingId
, COALESCE(t.count_employee, 0) count_employee
FROM building b
LEFT JOIN (SELECT d.buildingId
, COUNT(e.id) count_employee
FROM departments d
INNER JOIN employees e
ON d.departmentid = e.department
GROUP BY d.buildingId) t
ON b.buildingId = t.buildingId
If a building is attached with multiple departments and one employee is assigned with multiple departments then count building wise same employee is only onetime not multiple times. In that case DISTINCT keyword is used inside COUNT().
SELECT d.buildingId
, COUNT(DISTINCT e.id) count_employee
FROM departments d
INNER JOIN employees e
ON d.departmentid = e.department
GROUP BY d.buildingId
this is the schema Write a query to display the name of the department that has the maximum student count.
this is what is tried.
select d.department_name,count(s.student_id)
from department d left join student s
on d.department_id=s.department_id
group by d.department_name,d.department_id
order by d.department_name;
and i think there is something missing in my code
You're almost there.
Order the result in descending order on the number of students and then take the first row:
SELECT department_name
FROM
(
SELECT d.department_name,
COUNT(*) AS nr_students
FROM department d
JOIN student s
ON d.department_id = s.department_id
GROUP BY d.department_name
ORDER BY nr_students DESC
)
WHERE ROWNUM <= 1;
Based on the schema mentioned, you would have to make a join (INNER JOIN) to the department table from the staff table to get the name of the department.
If the name of the department is not desired and the counts can just be based on the department_id, then a join is not required.
The queries for both the scenarios is mentioned below.
Oracle SQL query for result with the department name, i.e. with INNER JOIN
SELECT D.DEPARTMENT_NAME, COUNT(S.DEPARTMENT_ID) AS STAFF_COUNT FROM **DEPARTMENT D, STAFF S** --INDICATES INNER JOIN IN ORACLE SQL
WHERE D.DEPARTMENT_ID = S.DEPARTMENT_ID
GROUP BY D.DEPARTMENT_NAME
ORDER BY STAFF_COUNT DESC
Oracle SQL query for result without the department name, just the department_id
SELECT S.DEPARTMENT_ID,COUNT(S.DEPARTMENT_ID) AS STAFF_COUNT FROM STAFF S
GROUP BY S.DEPARTMENT_ID
ORDER BY STAFF_COUNT DESC
Hope this helps. Cheers.
I tried this and it worked.
select department_name
from department d inner join student s
on s.department_id=d.department_id
having count(*) in (
select max(count(student_id))
from student s join department d
on d.department_id=s.department_id
group by d.department_id)
group by d.department_id,department_name;
Select * from (
SELECT D.DEPARTMENT_NAME, COUNT(S.DEPARTMENT_ID) AS STAFF_COUNT
FROM DEPARTMENT D, STAFF S
WHERE D.DEPARTMENT_ID = S.DEPARTMENT_ID
GROUP BY D.DEPARTMENT_NAME
ORDER BY STAFF_COUNT DESC)
where rownum=1;
This query will give department name that has maximum number of student count
I have an EmployeeDepartmetn juction table like this. I have all the departments in Depeartment table and employees in Employee table..
I want to get departments for an particular employee along with the all the departments available in depeartment table.
It should be like Select DepartmentId, DepartmentName, EmployeeID from Query.
Main criteria here is, Need to display NULL if the employee dont have that department. I am confused here...please help.
Please give Linq Query
Thanks in Advance
Put criteria in your left join:
Select distinct a.DeptID, b.DepartmentName, b.EmployeeID
From Department a
left join EmployeeDepartment b
on a.DeptID = b.DeptID and b.EmployeeID = 1 --insert employee ID here
It will show all departments (even those with no employees), then show the employee ID you chose in the third column only if that employee is assigned there.
You can do this with conditional aggregation:
select DeptId,
max(case when EmployeeId = 1 then EmployeeId end) as EmployeeId
from EmployeeDepartment ed
group by DeptId;
EDIT:
If you have a departments table as well:
select d.deptid, d.name, ed.employeeid
from Departments d left join
EmployeeDepartment ed
on d.deptid = ed.deptid and
ed.employeeid = 1;
I have two tables and I need to make a certain select.
First table is Employe that has colums Name *Departament_ID* and Salary
The second table is Departament that has colums Departament ID and *Departament_Name*
My SQL script has to get me the name of the departament, the maximum salay and minimum salary where Departament_ID is '30'
Something like this should do the trick (note: all spellings are exactly as you gave in your first post).
SELECT d.Department_Name AS name,
MAX(e.salary) AS max_salary,
MIN(e.salary) AS min_salary
FROM Department d
LEFT JOIN Employe e ON d.Department_ID = e.Department_ID
WHERE d.Department_ID = 30
SELECT d.department_name,
MIN(e.salary) AS 'Minimum Salary',
MAX(e.salary) AS 'Maximum Salary'
FROM department d,employee e
WHERE d.department_id=30 AND d.department_id=e.department_id
GROUP BY d.department_name
SELECT max(sal) as MaximumSalary
,min(sal) as MinimumSalary
,department.Departament_Name
,employee.Name
FROM employee
INNER JOIN department ON
employee.departmentid = department.department_id
WHERE department.department_id = 31
GROUP BY department.department_id
max and min function will give you the maximum and minimum value of the employee table for the salary column. This will require you to use GROUP BY because they need to calculate the maximum and minimum from a group of data witch in this case is the maximum/minimum by department. We group by department id because it's a unique key of the table. The inner join is here to join the two tables you have. It's an inner join because we want to have the department into the query.
SELECT d.Department_Name AS name,
MAX(e.salary) AS max_salary,
MIN(e.salary) AS min_salary
FROM Department d
Inner JOIN Employee ON d.Department_ID = e.Department_ID
WHERE d.Department_ID = 30
Department(DepartID,DepName)
Employees(Name,DepartID)
What i need is the Count of Employees in the Department with DepName.
If you are using SQL Server version 2005 or above, here is another possible way of getting employees count by department.
.
SELECT DPT.DepName
, EMP.EmpCount
FROM dbo.Department DPT
CROSS APPLY (
SELECT COUNT(EMP.DepartId) AS EmpCount
FROM dbo.Employees EMP
WHERE EMP.DepartId = DPT.DepartId
) EMP
ORDER BY DPT.DepName
Hope that helps.
Sample test query output:
I'd use an outer join rather than a subquery.
SELECT d.DepName, COUNT(e.Name)
FROM Department d
LEFT JOIN Employees e ON e.DepartID = d.DepartID
GROUP BY d.DepartID, d.DepName
SELECT d.DepName, COUNT(e.Name)
FROM Department d
LEFT JOIN Employees e
ON d.DepartID = e.DepartID
GROUP BY d.DepName
No need for a subquery.
SELECT dep.DepName, COUNT(emp.Name)
FROM DepName dep
LEFT OUTER JOIN Employees emp ON dep.DepartID = emp.DepartID
GROUP BY dep.DepName
SELECT COUNT(DISTINCT Name) FROM
Department AS d, Employees AS e
WHERE d.DepartID=e.DepartID AND d.DepName = '$thename'
And to avoid using a group by and save you a Sort operation in the queryplan:
SELECT
Department.DepName,
(SELECT COUNT(*)
FROM Employees
WHERE Employees.DepartID = Department.DepartID)
FROM
Department