Question

Need help with a query that I wrote:

I have three tables

Company

id     name
1      Gary's

Employee

id     name         company_id
1      Tim Jones       1
2      Sam Adams       1

reports to

employee_id      reports_to_id
     1                 2    

My current query is:

select 
   temp.company.name as comp_name, 
   temp.employee.name as employee_name, 
   temp.employee.id as employee_id 
from temp.employee, temp.employee
where temp.company.id = temp.employee.company_id and temp.company.id = 1

Which gives me the output of:

comp_name    employee_name     employee_id
 Gary's       Tim Jones           1

I need something like this:

comp_name     employee_name    reports_to
Gary's         Tim Jones        Sam Adams

What’s a good way to modify my query to do this? I have a query and then I take those results and run a second query against that result set (which is excessively unnecessary).

Answer 1

Assuming an employee only reports to one person then we could have (no link table)

Employee  (Id, Name, CompanyId, ReportsToId)
Company (Id, Name)

Then you could have a query similar to

select e.Name EmployeeName, c.Name CompanyName, r.Name ReportsTo
from
    Employee e
        inner join Company c on e.CompanyId = c.Id
        inner join Employee r on e.ReportsToId = r.Id
where
    e.CompanyId = 1

If the employee reports to multiple people then we would use a link table

Employee  (Id, Name, CompanyId)
EmployeeReportsTo (EmployeeId, ManagerId)
Company (Id, Name)

select e.Name EmployeeName, c.Name CompanyName, r.Name ReportsTo
from
    Employee e
        inner join Company c on e.CompanyId = c.Id
        inner join EmployeeReportsTo ert on ert.EmployeeId = e.Id
        inner join Employee r on ert.ManagerId = r.Id
where
    e.CompanyId = 1