I have 2 tables:
eomployee:
e_id | firstname | lastname
-------+-----------+-----------
10100 | Mark | Stevens
10101 | Alex | Watts
10102 | Hannah | Burton
and works_on:
employee_e_id | product_prod_nr | hours
---------------+-----------------+-------
10100 | 66000 | 40
10100 | 77211 | 37
10101 | 90210 | 67
I now want to get the e_id, firstname, lastname, hours of the person who is working the least hours. This is just sample data from the 2 tables.
I tried ti get it with limit 1, but that does not work when i have 2 people working 1 hour for example.
You can use window functions:
SELECT e_Id, firstname, lastname, hours
FROM (SELECT e.*,
MIN(hours) OVER () as min_hours
FROM eomployee e JOIN
works_on w
ON e.e_id = w.employee_e_id
) ew
WHERE hours = min_hours;
try like below by using window function
with cte as
(
select e.e_id,
e.firstname,e.lastname,w.hours,row_number() over(order by w.hours asc) rn
from eomployee e join works_on w on e.e_id=w.employee_e_id
) select * from cte where rn=1
Try this:
SELECT e.*,
max_hours_row.*
FROM eomployee e
INNER JOIN
(SELECT employee_e_id,
MIN(hours) AS time_min
FROM works_on
GROUP BY employee_e_id ) AS max_hours_row ON max_hours_row.employee_e_id = e.e_id
If you want the row with the least hours (= 37 in your example):
SELECT
e.e_id,
e.firstname,
e.lastname,
w.hours
FROM
eomployee e
JOIN works_on w ON e.e_id = w.employee_e_id
ORDER BY w.hours
LIMIT 1
If you want to get the row for cumulative working hours (in your example "10100" is working 37+ 40 = 77 hours):
SELECT
e_Id, firstname, lastname, hours
FROM (
SELECT
e.e_id,
e.firstname,
e.lastname,
w.hours,
SUM(hours) OVER (PARTITION BY e_id) as cum
FROM
eomployee e
JOIN works_on w ON e.e_id = w.employee_e_id
) s
ORDER BY cum
LIMIT 1
demo:db<>fiddle
Related
This question already has answers here:
Get top 1 row of each group
(19 answers)
Closed 4 months ago.
We have 2 Tables Employees and Department.
We want to show the maximum salary from each department and their corresponding employee name from the employee table and the department name from the department table.
Employee Table
EmpId | EmpName |salary |DeptId
101 shubh1 1000 1
101 shubh2 4000 1
102 shubh3 3000 2
102 shubh4 5000 2
103 shubh5 12000 3
103 shubh6 1000 3
104 shubh7 1400 4
104 shubh8 1000 4
Department Table
DeptId | DeptName
1 ComputerScience
2 Mechanical
3 Aeronautics
4 Civil
I tried doing it but was getting error
SELECT DeptName FROM Department where deptid IN(select MAX(salary),empname,deptid
FROM Employee
GROUP By Employee.deptid)
Error
Token error: 'Column 'Employee.EmpName' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause.' on server 4e0652f832fd executing on line 1 (code: 8120, state: 1, class: 16)
Can someone please help me.
select salary
,EmpName
,DeptName
from (
select e.salary
,e.EmpName
,d.DeptName
,rank() over(partition by e.DeptId order by e.salary desc) as rnk
from Employee e join Department d on d.DeptId = e.DeptId
) t
where rnk = 1
salary
EmpName
DeptName
4000
shubh2
ComputerScience
5000
shubh4
Mechanical
12000
shubh5
Aeronautics
1400
shubh7
Civil
Fiddle
Now that I know it's MS SQL Server, technically; we could use cross or outer Apply; it's a table value function not a join per say... but this will depend on the version of SQL Server; and if you want data if it doesn't exist in another
I find this the "Best" Design pattern to use for this type of query.
What the engine does is for each record in department, it runs a query for the employees Finding those in that department returning the 1 record having the max salary. With top we could specify with ties to return more than one. but we would need to know how to handle Ties of salary. Use top 1 with ties or order the results so you get the "Top" result you want.
Demo: dbfddle.uk
SELECT Sub.empName, Sub.Salary, D.DeptName
FROM Department D
CROSS Apply (SELECT Top 1 *
--(SELECT TOP 1 with Ties * -- could use this if we ties
FROM Employee E
WHERE E.DeptID = D.DeptID
ORDER BY Salary Desc) Sub --add additional order by if we don't want ties.
The cross apply gives us:
+---------+--------+-----------------+
| empName | Salary | DeptName |
+---------+--------+-----------------+
| shubh2 | 4000 | ComputerScience |
| shubh4 | 5000 | Mechanical |
| shubh5 | 12000 | Aeronautics |
| shubh7 | 1400 | Civil |
+---------+--------+-----------------+
Before window functions, before cross Apply or lateral... We'd write an inline view
It would get us the max salary for each dept, we then join that back to our base tables to find the employee within each dept with max salary...
Demo: DbFiddle.uk
SELECT E.*, D.*
FROM Employee E
INNER JOIN Department D
on E.DeptID = D.DeptID
INNER JOIN (SELECT MAX(SALARY) maxSal , DeptID
FROM Employee
GROUP BY DeptID) Sub
on Sub.DeptID = E.DeptID
and Sub.MaxSal = E.Salary
One has to do a join to get the department info an the employee info. However, we can eliminate the join for salarymax by using exists and correlation instead.
Demo DbFiddle.uk
SELECT E.*, D.*
FROM Employee E
INNER JOIN Department D
on E.DeptID = D.DeptID
WHERE EXISTS (SELECT MAX(Sub.SALARY) maxSal , Sub.DeptID
FROM Employee Sub
WHERE sub.DeptID=E.DeptID --correlation 1
GROUP BY Sub.DeptID
HAVING E.Salary = max(Sub.Salary)) --correlation 2
We could eliminate the last join too I suppose:
Demo: Dbfiddle.uk
SELECT E.*, (SELECT DeptName from Department where E.DeptID = DeptID)
FROM Employee E
WHERE EXISTS (SELECT MAX(Sub.SALARY) maxSal , Sub.DeptID
FROM Employee Sub
WHERE sub.DeptID=E.DeptID --correlation 1
GROUP BY Sub.DeptID
HAVING E.Salary = max(Sub.Salary)) --correlation 2
The top 3 give us this result:
+-----+---------+--------+--------+--------+-----------------+
| id | empName | salary | deptID | DeptID | DeptName |
+-----+---------+--------+--------+--------+-----------------+
| 101 | shubh2 | 4000 | 1 | 1 | ComputerScience |
| 102 | shubh4 | 5000 | 2 | 2 | Mechanical |
| 103 | shubh5 | 12000 | 3 | 3 | Aeronautics |
| 104 | shubh7 | 1400 | 4 | 4 | Civil |
+-----+---------+--------+--------+--------+-----------------+
The objective of the query is get a count of employees absent under each manager.
Attendance (Dates when employees are present)
id date
1 16/05/2020
2 16/05/2020
1 17/05/2020
2 18/05/2020
3 18/05/2020
Employee
id manager_id
1 2
2 3
3 NA
The desired output should be in this format:
Date manager_id Number_of_absent_employees
16/05/2020 NA 1
17/05/2020 3 1
17/05/2020 NA 1
18/05/2020 2 1
I have tried writing code but partially understood it, intuition being calculating total number of actual employees under each manager and subtracting it from number of employees present on given day. Please help me in completing this query, many thanks!
with t1 as /* for counting total employees under each manager */
(
select employee.manager_id,count(*) as totalc
from employee as e
inner join employee on e.employee_id=employee.employee_id
group by employee.manager_id
)
,t2 as /* for counting total employees present each day */
(
select Attendence.date, employee.manager_id,count(*) as present
from employee
Left join Attendence on employee.employee_id=Attendence.employee_id
group by Attendence.date, employee.manager_id
)
select * from t2
Left join t1 on t2.manager_id=t1.manager_id
order by date
Cross join the distinct dates from Attendance to Employee and left join Attendance to filter out the matching rows.
The remaining rows are the absences so then you need to aggregate:
select d.date, e.manager_id,
count(*) Number_of_absent_employees
from (select distinct date from Attendance) d
cross join Employee e
left join Attendance a on a.date = d.date and a.id = e.id
where a.id is null
group by d.date, e.manager_id
See the demo.
Results:
| date | manager_id | Number_of_absent_employees |
| ---------- | ---------- | -------------------------- |
| 16/05/2020 | NA | 1 |
| 17/05/2020 | 3 | 1 |
| 17/05/2020 | NA | 1 |
| 18/05/2020 | 2 | 1 |
Try this query. In first cte just simplify your code. And in the last query calculate absent employees.
--in this CTE just simplify counting
with t1 as /* for counting total employees under each manager */
(
select employee.manager_id,count(*) as totalc
from employee
group by manager_id
)
,t2 as
(
select Attendence.date, employee.manager_id,count(*) as present
from employee
Left join Attendence on employee.employee_id=Attendence.employee_id
group by Attendence.date, employee.manager_id
)
select t2.date,t2.manager_id, (t1.totalc-t2.present) as employees_absent from t2
Left join t1 on t2.manager_id=t1.manager_id
order by date
Select ec.manager_id, date, (total_employees - employee_attended) as employees_absent from
(Select manager_id, count(id) as total_employees
from employee
group by manager_id) ec,
(Select distinct e.manager_id, a.date, count(a.id) over (partition by e.manager_id, a.date) as employee_attended
from Employee e, attendence, a
where e.id = a.id(+)) ea
where ec.manager_id = ea.manager_id (+)
I guess this should work
I want to get the most recent date from joined tables with unique values in 2 columns. How do I do this? I have also tried the ranking (but John has the same rank) and tried rownum = 1, but I still get the same results below for some reason
Name ID Email DeptNo DeptScore OnDate
John A46 john#doe.com 100 50 5/11/2011
John A46 johndoe#aol.com 200 75 7/21/2015
Alice B33 alice#hotmail.com 100 50 4/15/2014
I want to get the following:
Name ID Email DeptNo DeptScore OnDate
John A46 johndoe#aol.com 200 75 7/21/2015
Alice B33 alice#hotmail.com 100 50 4/15/2014
My query
select distinct e.name, e.id, e.email, d.deptno, d.deptscore, d.ondate
from
emp e
inner join dept d on
d.deptno = e.dnum
and d.ondate = e.livedate
and d.ondate = (select max(m.ondate)
from dept m
where d.ondate = m.ondate)
--where e.id in ('A46','B33')
Try to use the below Query, it will solve your problem.
select name,
id,
email,
deptno,
deptscore,
ondate
from (select e.name,
e.id,
e.email,
d.deptno,
d.deptscore,
d.ondate,
rank() over(partition by e.id,e.name order by d.ondate desc) rn
from emp e join
dept d
on d.deptno = e.dnum and d.ondate = e.livedate
) s
where rn = 1;
Output:
NAME ID EMAIL DEPTNO DEPTSCORE ONDATE
John A46 johndoe#aol.com 200 75 21-JUL-15
Alice B33 alice#hotmail.com 100 50 15-APR-14
I am trying to select records that appear more than once and are part of a specific department plus other departments.
So far the query that I have is this:
SELECT employeeCode, employeeName
FROM
Employees
WHERE
Department <> 'Technology'
AND employeeCode IN (SELECT employeeCode
FROM Employees
GROUP BY employeeCode HAVING COUNT(*) > 1)
The problem is that I want to select employees which are part of the Technology department, but they also participate in other departments.
So, they must be from the Technology department, but they could also be from the Household department. In the database it could look like:
1 | A1 | Alex | Technology
2 | A2 | Thor | Household
3 | A3 | John | Cars
4 | A3 | John | Technology
5 | A4 | Kim | Technology
6 | A4 | Kim | Video Games
So basically the query should return:
A3 | John |
A4 | Kim |
I think it's a small part that I am missing but..
Any ideas on how to filter/sort it so that it always uses the technology and the other departments?
Btw, I tried searching but I couldn't find a problem like mine..
If you want employees that could be in the technology department and another department:
select e.employeeCode, e.employeeName
from employees e
group by e.employeeCode, e.employeeName
having sum(case when e.department = 'Technology' then 1 else 0 end) > 0 and
count(*) > 1;
This assumes no duplicates in the table. If it can have duplicates, then use count(distinct department) > 1 rather than count(*) > 1.
Try this:
SELECT E.employeeCode, E.employeeName
FROM Employees E
INNER JOIN (SELECT DISTINCT E1.employeeCode, E1.employeeName
FROM Employees E
WHERE E.Department = 'Technology'
) AS A ON E.employeeCode = A.employeeCode AND E.employeeName = A.employeeName
GROUP BY E.employeeCode, E.employeeName
HAVING COUNT(*) > 1;
You can use EXISTS with correlated sub-query joining on the same table with different condition.
SELECT e1.employeeCode, e1.employeeName
FROM Employees e1
WHERE e1.Department = 'Technology'
AND EXISTS (SELECT * FROM Employees e2
WHERE e1.employeeCode = e2.employeeCode
AND e2.Department <> 'Technology')
This will work for your case:
SELECT a.employeeCode, a.employeeName
FROM Employees a, Employees b
WHERE
a.Department = 'Technology'
AND
b.Department <> 'Technology'
AND
a.employeeCode = b.employeeCode
AND
a.employeeID <> b.employeeID
I have two tables
Employee:
Empid Ename Eage Eadd Ephone
1 x 23 b 677
2 y 24 h 809
3 z 34 u 799
Department:
Did fkEmpid dname ddescription
123 1 test test
234 1 test1 test1
667 2 hello hello
Finally I want something like this
Ename Eage Eadd Ephone dname
x 23 b 677 test,test1
y 24 h 809 hello
z 34 u 799 null
Please help me with the SQL
It certainly would be nice to know the target RDBMS. But this question is asked so often so let's try and list'em all (at least popular ones) side by side.
For SQL Server:
SELECT e.Ename, e.Eage, e.Eadd, e.Ephone, d.dname
FROM Employee e LEFT JOIN
(
SELECT fkEmpid,
STUFF((SELECT ',' + dname
FROM Department
WHERE fkEmpid = t.fkEmpid
FOR XML PATH('')) , 1 , 1 , '' ) dname
FROM Department t
GROUP BY fkEmpid
) d
ON e.Empid = d.fkEmpid
Here is SQLFiddle demo
For Mysql, SQLite, HSQLDB 2.X:
SELECT e.Ename, e.Eage, e.Eadd, e.Ephone, d.dname
FROM Employee e LEFT JOIN
(
SELECT fkEmpid,
GROUP_CONCAT(dname) dname
FROM Department t
GROUP BY fkEmpid
) d
ON e.Empid = d.fkEmpid
Here is SQLFiddle demo (MySql)
Here is SQLFiddle demo (SQLite)
For Oracle 11g:
SELECT e.Ename, e.Eage, e.Eadd, e.Ephone, d.dname
FROM Employee e LEFT JOIN
(
SELECT fkEmpid,
LISTAGG (dname, ',') WITHIN GROUP (ORDER BY dname) dname
FROM Department t
GROUP BY fkEmpid
) d
ON e.Empid = d.fkEmpid
Here is SQLFiddle demo
For PostgreSQL 9.X:
SELECT e.Ename, e.Eage, e.Eadd, e.Ephone, d.dname
FROM Employee e LEFT JOIN
(
SELECT fkEmpid,
string_agg(dname, ',') dname
FROM Department t
GROUP BY fkEmpid
) d
ON e.Empid = d.fkEmpid
Here is SQLFiddle demo
Output in all cases:
| ENAME | EAGE | EADD | EPHONE | DNAME |
---------------------------------------------
| x | 23 | b | 677 | test,test1 |
| y | 24 | h | 809 | hello |
| z | 34 | u | 799 | (null) |
Considering RDBMS as SQL SERVER 2008
select E.Ename,E.Eage,E.Eadd,E.Ephone,D.dname
into Table1
from Employee E
left join Deparment D on E.Empid=D.fkEmpid
select t1.[Ename], t1.[Eage], t1.[Eadd], t1.[Ephone],
STUFF((
SELECT ', ' + t2.dname
FROM Table1 t2
WHERE t2.Ename = t1.Ename
AND t2.Eage=t1.Eage
AND t2.Eadd=t1.Eadd
AND t2.Ephone=t1.Ephone
FOR XML PATH (''))
,1,2,'') AS Names
FROM Table1 t1
GROUP BY t1.Ename,t1.[Eage], t1.[Eadd], t1.[Ephone];
SQL FIDDLE