SQL query to build search form

Question

I have a table Department, with primary key DeptId.
Table: Department
DeptId Text
1 xx
2 yy
3 zz
I have another table Person, with key (not primary, and not unique) PersonId, and foreign key DeptId
Table: Person
PersonId DeptId
10 1
11 1
11 2
12 2
I want to build a search form, with search fields PersonId and DeptId, so that in the resulting table, some rows from the Department table are returned. It should obey the following:
- If both PersonId and DeptId are selected, and there is a row in the table Person that matches the selection, the row from the Department table should be returned.
- If only PersonId is selected, any row in Department table that matches a DeptId corresponding to that PersonId should be returned.
- If only DeptId is selected, return that row from Department exactly once (even if that DeptId doesn't appear in Person table, like DeptId 3 in this example)
- If neither is selected, return all rows from Department
I'm using JDeveloper 11.1.2.2.0.
Thanks,
Zach

Answer 1

Hi Navaneeth,
Taking the example from your link:
SELECT org.org_id, org.name FROM organisations org WHERE EXISTS
(SELECT 1 FROM events evt WHERE evt.org_id = org.org_id
AND evt.contact_name = 'Eddie Harris')
Let's say I make evt.contact_name a dropdown list, and when I query it, I leave it unselected. Would it return org.org_id, org.name from a row that has no corresponding event row?