i`m new in SQL and i need a tip. I got 2 tables ( employee and department ),
employee table as E:
id (int), name(nvarchar), gender(nvarchar), departmentID(int), dateofbirth(datetime)
department table as D :
dep_id(int), name(nvarchar), location(nvarchar), boss_id(int)
That`s what i need as output table:
E.id / E.name / D.name / D.location / (and last which i cant get with simple join is:) D.boss.name (not simple boss id but real employee name from E table)
Just simple question for advanced people :-)
Join the table a second time for the boss. (This is assuming that boss_id FK's to Employee)
SELECT
E.Id,
E.Name,
D.Name,
D.Location,
B.Name
FROM Employee E
INNER JOIN Department D on E.DepartmentID = D.Dep_id
INNER JOIN Employee B ON D.Boss_id = B.Id
You can write a query using cte as well:
WITH CTE AS(
Select
e.ID,
e.name,
d.boss_id,
d.Location as DepartmentLocation,
d.name as DepartmentName
From Employee e
INNER JOIN Department d on d.boss_id =E.id
)
Select c.id, c.name, e.name as BossName, c.DepartmentLocation, c.DepartmentName
from cte c
Inner Join Employee e1 on e1.id=c.boss_id
SELECT e.Id, e.Name, d.Name, d.Location,
(
SELECT e2.Name
FROM tblEmployee as e2
WHERE e2.id = d.boss_id
) AS [Boss name]
FROM tblEmployee as e
INNER JOIN tblDepartment as d
ON e.DepartmentID = d.dep_ID
Related
Can someone help me in writing Oracle SQL Query for the following scenario:
Company can have multiple departments.
Each department can have multiple Employees.
Employee need not have department assigned but company Id is must.
This is the output I am trying for:
This is the query I have tried So far:
SELECT C.id Company_Id,
C.name Company_Name,
D.id Department_Id,
D.name Department_Name,
E.id Employee_Id,
E.name Employee_Name
FROM Company C
FULL OUTER JOIN Department D
ON D.CompanyId = C.Id
FULL OUTER JOIN Employee E
ON E.CompanyId = C.Id AND E.DepartmentId = D.Id
ORDER BY Company_Id,Department_Id,Employee_Id;
But it gives this output:
EDIT:
Sql fiddle : http://sqlfiddle.com/#!4/df238/3/0
The trick is to convert ON E.CompanyId = C.Id AND E.DepartmentId = D.Id join condition to
ON E.CompanyId = C.Id AND ( E.DepartmentId = D.Id OR E.DepartmentId is null )
SELECT C.id Company_Id,
C.name Company_Name,
D.id Department_Id,
D.name Department_Name,
E.id Employee_Id,
E.name Employee_Name
FROM Company C
FULL OUTER JOIN Department D
ON D.CompanyId = C.Id
FULL OUTER JOIN Employee E
ON E.CompanyId = C.Id AND ( E.DepartmentId = D.Id OR E.DepartmentId is null )
ORDER BY Company_Id,Department_Id,Employee_Id;
Demo
I have a table named employee. It includes managers and employees. There is also birthdate column and i need to find "older employees than THEIR managers". How can I do it? Could you give me some clue?
You could use an inner join to the same table:
select e.*
from employees e
inner join employees m
on e.managerid = m.id
and e.birthdate < m.birthdate
or exists() in the where:
select e.*
from employees e
where exists (
select 1
from employees m
where e.managerid = m.id
and e.birthdate < m.birthdate
)
If your employees structure is something like:
id,
name,
birthdate,
manager_id
This could be a solution:
select id, name
from employees e
where
exists
(select *
from employees m
where
m.id = e.manager_id and
m.birthdate > e.birthdate);
I have 2 tables,
The first one is called emp, and has 2 columns called id and name
The second one is called dep, and has columns called id and empid and nameOfDep
if I want to list all emp that have X dep, but don't have Y dep
This is an example I use
Select e.id, e.name
from emp e
where e.id in (Select empid from deptid where deptid=X)
and e.id not in (Select empid from deptid where deptid=Y);
How I can make it using JOIN instead of with subqueries?
An IN can be converted into an INNER JOIN. A Not IN can be converted to LEFT JOIN / NULL Test. Sometimes called an ANTI JOIN.
SELECT e.id,
e.name
FROM emp e
INNER JOIN deptid D_X
ON e.empid = d_x.empid
AND deptid = 'X'
LEFT JOIN deptid D_Y
ON e.empid = d_Y.empid
AND deptid = 'Y'
WHERE d_Y.empid IS NULL
Also I'm making the assumption that when you wrote deptid = X that you meant X to be a literal string and not a field name
SELECT e.id, e.name
FROM emp e
INNER JOIN dep d ON (e.deptID = d.deptID AND d.deptID NOT y)
Add the Department ID to the employee record and then join on that.
EDIT
My bad, updated.
EDIT
Helps to read, go with Conrad's answer.
I have a disjoint relationship among my tables: Employee(empId PK, name), HourlyEmployee(empId PK FK, hourlySalary) empId is a reference to Employee.empId,
MonthlyEmployee(empId Pk FK, monthlySalary) empId is a reference to Employee.empId.
How can I create a query resulting AllEmployees(empId,name,hourlySalary,monthlySalary).
For all hourly employees monthlySalary will be null and for all monthly employess hourly salary will be null
Regards,
Tural
Use outer joins to get all employees no matter if they exist in HourlyEmployee or MonthlyEmployee (or neither of them).
select e.empid, e.name, h.hourlysalary, m.monthlysalary
from employee e
left outer join hourlyemployee h on h.empid = e.empid
left outer join monthlyemployee m on m.empid = e.empid;
select e.empid, e.name, h.hourlysalary, m.monthlysalary
from employee e
left outer join hourlyemployee h on h.empid = e.empid
left outer join monthlyemployee m on m.empid = e.empid
where (h.hourlysalary is null) or (m.monthlysalary is null);
I have a query that I need to execute that I do not know how to structure.
I have a table called Employees. I have another table called Company. There is a third table called Files. As you can imagine, a Company has Employees, and Employees have Files.
I need to list out all of the Employees in my database. The challenge is, I need to list the total number of Files in the same company as the Employee. I have tried variations on the following without any luck:
SELECT
e.FirstName,
e.LastName,
e.Company,
(SELECT COUNT(*) FROM Files f WHERE f.EmployeeID IN (SELECT [ID] FROM Employees e2 WHERE e2.CompanyID=e.CompanyID)) as 'FileCount'
FROM
Employees e
What am I doing wrong? Thank you!
Try this:
SELECT
e.FirstName,
e.LastName,
e.Company,
(
SELECT COUNT(*)
FROM Files f
JOIN Employees e2 ON f.EmployeeID = e2.id
WHERE e2.CompanyID = e.CompanyID
) as 'FileCount'
FROM
Employees e
There are a lot of ways to get that. If the performance is a concern, this is more optimal according to estimated execution plan costs.
SELECT
e.FirstName,
e.LastName,
e.Company,
COUNT(f.FileId)
FROM
Employees e
INNER JOIN Files f ON e.EmployeeID = f.EmployeeID
GROUP BY
e.FirstName,
e.LastName,
e.Company
A solution with no correlation in SELECT clause. Probably quicker...
SELECT
e.FirstName,
e.LastName,
e.Company,
foo.FileCount
FROM
Employees e
JOIN
(
SELECT
COUNT(*) AS FileCount, --OR COUNT(DISTINCT something) ?
e2.Company, f.EmployeeID
FROM
Files f JOIN Employees e2 ON f.EmployeeID = e2.id
GROUP BY
e2.Company, f.EmployeeID
) foo ON e.Company = foo.Company AND e.id = foo.EmployeeID
How about:
SELECT
e.FirstName,
e.LastName,
e.Company,
select count(*) from Files f, Employees e where f.EmployeeID=e.EmployeeID and e.CompanyID=emp.CompanyID
FROM
Employees emp
WITH FilesPerCompany (CompanyID, NumberOfFiles)
AS (SELECT c.ID AS CompanyID,
COUNT(*) AS NumberOfFiles
FROM Companies c
INNER JOIN Employees e ON c.ID = e.CompanyID
INNER JOIN Files f ON e.ID = f.EmployeeID
GROUP BY c.ID
)
SELECT e.FirstName,
e.LastName,
e.Company,
COALESCE(s.NumberOfFiles, 0) AS NumberOfFilesPerCompany
FROM Employees e
LEFT JOIN FilesPerCompany s
ON s.CompanyID = e.CompanyID
The following statement uses recursive joins to iterate down employees who manage other employees who manage other employees .... etc. Our structure is a little convoluted as the management structure is role based which actually allows an employee to have more than 1 manager. You can add a reference to Files within this recursion.
WITH Manager as
(SELECT c.Forenames + ' ' + c.Surname as Employee,
c2.Forenames + ' ' + c2.Surname AS Manages,
c.accountid AS AccountID, c.[Status] AS [Status]
FROM [intranet].[dbo].[tblContact] c
LEFT JOIN tblContactPost cp ON cp.contactid = c.contactid
LEFT JOIN tblPost p ON p.ParentRoleId = cp.RoleID AND p.ParentPostArea = cp.PostArea AND p.ParentPostNo = cp.PostNo
INNER JOIN tblContactPost cp2 ON cp2.RoleId = p.RoleId AND cp2.PostArea = p.PostArea AND cp2.PostNo = p.PostNo
INNER JOIN tblContact c2 ON c2.ContactID = cp2.ContactId
)
,jn AS
(SELECT Employee, Manages
FROM Manager
Where AccountID = 'ad\lgardner' AND [Status] = 'A'
UNION ALL
SELECT c.Employee, c.Manages
FROM jn as p JOIN Manager AS c
ON c.Employee = p.Manages
)
SELECT jn.Employee, jn.Manages
From jn
Order BY 1