Friday, March 23, 2012

Multiple inner joins on same field or nested query?

Hi,

I'm wondering how I can structure an SQL statement to perform either a multiple join on a single table, or possibly using a sub-query. Basically, I've got one table in which both fields are foreign keys to another table, as follows:

Table #1

employee_id (pk)
employee_name

Table #2
teamleader_employee_id
backup_employee_id


both fields in table 2 need to do a lookup in table 1 to get the name of the actual employee. Do I need to use nested queries to accomplish this? Is it possible to do two inner joins on the same table? (I've tried this, unsuccessfully!) Any help is greatly appreciated!

-PJtwo joins to the same table, using table aliases to distinguish which table the rows are from, and column to distinguish the columns in the result set
select lead.employee_name as teamleader
, bkup.employee_name as backup
from table2
inner
join table1 as lead
on teamleader_employee_id = lead.employee_id
inner
join table1 as bkup
on backup_employee_id = bkup.employee_id|||Thank you very much. Works like a charm!

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