Re: Create a Trigger for an existing View

On 10 Apr., 17:56, "EdStevens" <quetico_...@xxxxxxxxx> wrote:
On Apr 10, 8:54 am, "Dean Tomasevic" <dean.tomase...@xxxxxxxxxxxxxx>
wrote:



On 10 Apr., 15:26, "EdStevens" <quetico_...@xxxxxxxxx> wrote:

On Apr 10, 7:25 am, "Dean Tomasevic" <dean.tomase...@xxxxxxxxxxxxxx>
wrote:

On 10 Apr., 06:45, "Vladimir M. Zakharychev"

<vladimir.zakharyc...@xxxxxxxxx> wrote:
On Apr 10, 2:43 am, "Dean Tomasevic" <dean.tomase...@xxxxxxxxxxxxxx>
wrote:

Hi!

I created a view from the two existing tables (DEMO_USERS and
DEMO_ORDERS).

Code:
CREATE VIEW DEMO_MY_TEST AS
SELECT DEMO_USERS.USER_ID, DEMO_ORDERS.ORDER_ID
FROM DEMO_USERS
INNER JOIN DEMO_ORDERS
ON DEMO_ORDERS.USER_ID = DEMO_USERS.USER_ID

So now my job is to update my view if anybody will take an new order.
As example:
If user X with the USER_ID 2 will complete a new order my trigger must
updating the view.

But i have problems with the trigger, i know that i must write an
updating trigger, but the actuator for the trigger is an "insert into"
into the DEMO_ORDERS table, because only if a new order will insert
into the DEMO_ORDERS table, then the trigger must be activated and
updating the view.

Thanks a lot.

Dean Tomasevic

I may be reading it wrong, but there's no need to update the view - it
will pick up changes from the underlying tables automatically. A view
is just a stored query, it doesn't immediately materialize and store
the result set until "updated"; every time you query the view, the
view statement will be re-executed against current data. So when
someone adds an order, its ORDER_ID will be returned when you SELECT *
FROM DEMO_MY_TEST without any extra coding effort.

Hth,
Vladimir M. Zakharychev
N-Networks, makers of Dynamic PSP(tm)
http://www.dynamicpsp.com

hi.

You're right, the view will auto updating if i klick on the view.
but what is if i create a new table,

Why are you creating a new table?

and insert the result of
"CREATE VIEW DEMO_MY_TEST AS

<snip>

into my new table.

The result of CREATE VIEW is that you get a view - a predefined query
- created. Nothing more. Has nothing to do with the absence or
existence of any rows on any table. CREATE VIEW does not produce any
result to insert into a table

Then i need a trigger which auto statrts if the DEMO_ORDERS table has
a new entry, because then
I must insert the new entry of DEMO_ORDERS over a trigger into my new
table.

Sounds like you are createing a whole new table every time a row is
insterted into DEMO_ORDERS?

i hope you understand what i mean ;)

No, we don't. Perhaps if you explained the business problem you are
trying to solve instead of the technique you think you need to use to
solve it. Right now your design direction sounds like one big FUBAR.

Well i even read my task

Always a good place to start ....

and my job is to insert the result of my
inner join into a new table and updating the new table every time if a
new entry will make in the DEMO_ORDERS table (thats a test which i
must make for the school..), and this i must realise with a trigger, i
think.
Because if a new entry will make in the DEMO_ORDERS table the trigger
must be activated and insert the new ORDER entry into my own created
table.

Dean- Hide quoted text -

- Show quoted text -

Still sounds like a FUBAR design. Perhaps you are mis-understanding
the nature of this homework assignment. Can you post the task that
you 'even read'? Not your interpretation. The text as it was
presented to you.

BTW, we won't do your homework for you, but we will try to get you
back on track.

The Task:
"Please write a inner join for the tables DEMO_USERS and DEMO_ORDERS.
The required information are the USER_ID and ORDER_ID.
If anybody take a new order you must be able to see it in your result,
but
don't use a view!
Try it with a inner join and a trigger."

Thats the task, and i think one result can be that i create a new
table,
write a inner join (look at my first post) and put the result into my
table.
And if anybody take a new order my trigger will put the new order
into my new table.

Did i understand it correctly?

Thanks.

Dean T.

.

Relevant Pages

  • Re: Create a Trigger for an existing View
    ... INNER JOIN DEMO_ORDERS ... If user X with the USER_ID 2 will complete a new order my trigger must ... I must insert the new entry of DEMO_ORDERS over a trigger into my new ... and when a transaction starts. ...
    (comp.databases.oracle.server)
  • Re: Create a Trigger for an existing View
    ... If user X with the USER_ID 2 will complete a new order my trigger must ... updating trigger, but the actuator for the trigger is an "insert into" ... is just a stored query, it doesn't immediately materialize and store ... I must insert the new entry of DEMO_ORDERS over a trigger into my new ...
    (comp.databases.oracle.server)
  • Re: Create a Trigger for an existing View
    ... On 10 Apr., 06:45, "Vladimir M. Zakharychev" ... INNER JOIN DEMO_ORDERS ... If user X with the USER_ID 2 will complete a new order my trigger must ... updating trigger, but the actuator for the trigger is an "insert into" ...
    (comp.databases.oracle.server)
  • Re: Create a Trigger for an existing View
    ... INNER JOIN DEMO_ORDERS ... If user X with the USER_ID 2 will complete a new order my trigger must ... updating trigger, but the actuator for the trigger is an "insert into" ... I must insert the new entry of DEMO_ORDERS over a trigger into my new ...
    (comp.databases.oracle.server)
  • Re: Create a Trigger for an existing View
    ... INNER JOIN DEMO_ORDERS ... If user X with the USER_ID 2 will complete a new order my trigger must ... updating trigger, but the actuator for the trigger is an "insert into" ... is just a stored query, it doesn't immediately materialize and store ...
    (comp.databases.oracle.server)