Query creation problem

Question

Hi, I need to create a query that returns a cursor to a web client. The cursor must return 3 columns from a query, so that it can display a list of tick boxes. The tickboxes have 3 states:- visible, enabled, and selected.
In my example, I need to return a cursor so that it can display all 3 possible screens (i.e. sales, purchase, admin), for each of these screens a method of identifying whether the role allows the tick box to be enabled, and finally a method of ticking (selecting) the tick box according to the dept_id.
So far i have this, which does everything i need it to do, except for identifying whether to tick the box.
WITH screen AS
(SELECT 1 id, 'sales'    screen_desc, 103 dept_id,  501 role_id from dual union all
SELECT 2 id, 'purchase' screen_desc, 101 dept_id,  503 role_id from dual union all
SELECT 3 id, 'admin'    screen_desc, 103 dept_id,  503 role_id from dual ),
dept AS
(SELECT 101 id, 'marketing' dept_desc from dual union all
SELECT 102 id, 'management' dept_desc from dual union all
SELECT 103 id, 'IT' dept_desc from dual ),
role AS
(SELECT 501 id, 'junior'     role_desc from dual union all
SELECT 502 id, 'supervisor' role_desc from dual union all
SELECT 503 id, 'manager'    role_desc from dual)
select DISTINCT screen_desc, 'Y' enabled /*,'N' selected*/ from screen,dept,role
where dept.id        = screen.dept_id
AND   role.id        = screen.role_id
AND   dept_desc      = 'IT'
AND   role.role_desc = 'manager'
UNION
(select DISTINCT screen_desc, 'N' enabled/*, 'N' selected*/ from screen,dept,role
where dept.id       = screen.dept_id
AND   role.id       = screen.role_id
MINUS
select DISTINCT screen_desc, 'N' enabled/*, 'N' selected*/ from screen,dept,role
where dept.id        = screen.dept_id
AND   role.id        = screen.role_id
AND   dept_desc      = 'IT'
AND   role.role_desc = 'manager')Can anybody understand what i'm after, and secondly return the results i require, with the tables provided (i can't change the table relationships).
ta
David

Answer 1

Well this is what I get
SQL> WITH screen AS
  2  (SELECT 1 id, 'sales'    screen_desc, 103 dept_id,  501 role_id from dual union all
  3   SELECT 2 id, 'purchase' screen_desc, 101 dept_id,  503 role_id from dual union all
  4   SELECT 3 id, 'admin'    screen_desc, 103 dept_id,  503 role_id from dual )
  5  dept AS
  6  (SELECT 101 id, 'marketing' dept_desc from dual union all
  7   SELECT 102 id, 'management' dept_desc from dual union all
  8   SELECT 103 id, 'IT' dept_desc from dual ),
  9  role AS
10  (SELECT 501 id, 'junior'     role_desc from dual union all
11   SELECT 502 id, 'supervisor' role_desc from dual union all
12   SELECT 503 id, 'manager'    role_desc from dual)
13   select DISTINCT screen_desc, 'Y' enabled ,decode (dept_desc, 'IT', 'Y','N') selected from screen,dept,role
14   where dept.id        = screen.dept_id
15   AND   role.id        = screen.role_id
16   AND   dept_desc      = 'IT'
17   AND   role.role_desc = 'manager'
18  UNION
19  (select DISTINCT screen_desc, 'N' enabled, decode (dept_desc, 'IT', 'Y','N') selected from screen,dept,role
20   where dept.id       = screen.dept_id
21   AND   role.id       = screen.role_id
22  MINUS
23  select DISTINCT screen_desc, 'N' enabled, decode (dept_desc, 'IT', 'Y','N') selected from screen,dept,role
24   where dept.id        = screen.dept_id
25   AND   role.id        = screen.role_id
26   AND   dept_desc      = 'IT'
27   AND   role.role_desc = 'manager')
28  /
SCREEN_D E S
admin    Y Y
purchase N N
sales    N Y
SQL>So either your test data doesn't tie up the way you think it does, or you need to rework the precedence of your set operators.
By the way, the DISTINCTs are unnecessary - UNION gives your unique values anyway.
Cheers, APC
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