So I have three tables: Employee, Secretary and Manager
Given Schema
The Employee table has the following columns:
Employee_Number
Name
Home Address
Telephone Number
The Secretary table contains:
Secretary_Number
Employee_Number (linked with foreign key to Employee table)
Manager_Number (linked with foreign key to Manager table)
The Manager table contains:
Manager_Number
Employee_Number (linked with foreign key to Employee table)
What's required and what I tried
I am trying to do a JOIN so that I can see following columns:
Secretary's Number
Secretary's Name
Manager's Number
Manager's Name
I have the following join statement, which shows all the columns, and shows the Secretary's name and number, as well as the Manager Number:
SELECT
SECRETARY.SECRETARY_NUMBER,
SECRETARY.EMPLOYEE_NUMBER AS SECRETARY_EMPLOYEE,
EMPLOYEE.NAME AS SECRETARY_NAME,
SECRETARY.MANAGER_NUMBER,
MANAGER.EMPLOYEE_NUMBER AS MANAGER_EMPLOYEE,
EMPLOYEE.NAME AS MANAGER_NAME
FROM SECRETARY, MANAGER, EMPLOYEE
WHERE SECRETARY.MANAGER_NUMBER = MANAGER.MANAGER_NUMBER
AND SECRETARY.SECRETARY_NUMBER = EMPLOYEE.EMPLOYEE_NUMBER
AND MANAGER.EMPLOYEE_NUMBER = EMPLOYEE.EMPLOYEE_NUMBER;
Problem
But I can't get the Manager's Name to show up, or not repeat the same info as Secretary Name.
Any help would be greatly appreciated!
SELECT
s.SECRETARY_NUMBER,
s.EMPLOYEE_NUMBER AS SECRETARY_EMPLOYEE,
e.NAME AS SECRETARY_NAME,
s.MANAGER_NUMBER,
m.EMPLOYEE_NUMBER AS MANAGER_EMPLOYEE,
e2.NAME AS MANAGER_NAME
FROM
SECRETARY s
INNER JOIN
EMPLOYEE e
ON
e.EMPLOYEE_NUMBER = s.EMPLOYEE_NUMBER
INNER JOIN
MANAGER m
ON
m.EMPLOYEE_NUMBER = s.MANAGER_NUMBER
INNER JOIN
EMPLOYEE e2
ON
e2.EMPLOYEE_NUMBER = m.EMPLOYEE_NUMBER;
Related
I need to join two tables together to create a table with columns for employee id, employee name and their boss' name.
The 'hier' table
The 'employees' table
The query I wrote is almost working, putting an employee name in the right spot, but not the right employee:
SELECT em.emp_id, em.emp_name, em.emp_name AS boss_name
FROM employees em
LEFT JOIN hier h ON (h.boss_id = em.emp_name)
Which outputs:
I need to have each person's boss to have the right name, and in the case of Big Boss, 'N/A'. Like so:
You need a self join with Employee table
SELECT em.emp_id, em.emp_name, e1.emp_name AS boss_name
FROM employees em
LEFT JOIN employees em1 ON em.boss_id = em1.emp_id
I am trying to get a list of all the employee names and their managers and I cannot figure out how to do it. I have attached the relational model.
In DEPT we know the department number (dept_nbr) which is attached to EMPLOYEE through emp_dept and we know the department manager (dept_mgr) which is attached to EMPLOYEE through emp_nbr
select
mgr.emp_nbr ManagerID,
emp.emp_nbr EmployeeID,
emp.emp_lname, emp.emp_fname,
mgr.emp_lname as mgr_lname, mgr.emp_fname as mgr_fname
from
dept
inner join employee as mgr on dept.dept_mgr = mgr.emp_nbr
inner join employee as emp on dept.dept_nbr = emp.emp_dept
I have a table named Employee with columns:
employee_name
Street
City`.
Also have another table named 'works' with columns:
employee_name,
company_name
salary`
Here employee_name in works is a foreign key of the column employee_name in Employee table.
Now how do I find the street and city of 'Employee' table on a specific company_name?
The query will be something like:
select street, city from Employee where company_name (in works table) ='XYZ';
I'm working on Oracle 10g database server.
You can use an inner join
select
Employee.employee_name
, Employee.street
, Employee.city
from Employee
INNER JOIN works on Employee.employee_name = works-employee_name
where works.company_name ='xyz'
Suppose I have an employee table. I have Name and Manager columns. Say there are 10 employees of which 2 are managers. So Name will have 10 names and Manager name would be in Manager column.
How to use self join? I am just learning self join
To perform a self join, you simply give the same table a different alias.
For example, in your employee table you would have a managerid - which stores the id of the manager.
Then to get the manager's name - you just self join to the employee table on managerid - using a different alias (I have used m in the example below):
For example, your table would look like this:
CREATE TABLE Employees (id INT, Name VARCHAR(20), ManagerId INT);
To get the Employee's Name and his/her Manager's Name, you would do something like this:
SELECT
e.Name AS EmployeeName,
ISNULL(m.Name, 'No Manager') AS ManagerName
FROM employee e
LEFT JOIN employee m on m.id = e.ManagerId
If you want to learn more about self joins - see here
I have 2 tables: 1st holds employees (of ones in any position) and the 2nd holds manager employee relations with id numbers.
I want to write a query like
1st field: name(employee),
2nd field: name(manager)
How can I do that?
No nested queries required, just use standard joins:
select e.*, m.*
from
employee e
left join employee_managers em
on e.id = em.emp_id
left join employee m
on m.id = em.man_id
Each row will contain all fields of employee (possibly several rows for one employee if it has several associated managers) and all fields of his corresponding manager (or NULLs if employee has no manager).
You can do that with one table:
Employee
--------
EmployeeId int
Name varchar(50)
ManagerId int
ManagerId points to the manager's entry in the same table. The CEO will have a ManagerId of null. An example table definition:
create table Employees (
EmployeeId int auto_increment primary key
, Name varchar(50)
, ManagerId int
, foreign key (ManagerId) references Employees(EmployeeId)
);
With some example data:
insert into Employees (Name) select 'The Chief';
insert into Employees (Name, ManagerId) select 'Grunt 1',
(select EmployeeId from Employees where Name = 'The Chief');
insert into Employees (Name, ManagerId) select 'Grunt 2',
(select EmployeeId from Employees where Name = 'The Chief');
insert into Employees (Name, ManagerId) select 'Secretary',
(select EmployeeId from Employees where Name = 'The Chief');
To find the name of the second Grunt's manager, you could query like:
select mgr.Name
from Employees mgr
inner join Employees grunt
on grunt.managerid = mgr.employeeid
where grunt.name = 'Grunt 2';