Hi. I want to create a trigger that only allows delete from table A if
corresponding record in table B does not exist. Any idea on how this
can be done? Thanks, Kenneth.
6  7643 
Is there a column in table B that references the primary key of table A?
If so, won't the constraint prevent the deletes you want to prevent?
Don't you wanna use referential integrity constraints to achieve this? ke************* **@telenor.com (Kenneth Osenbroch) wrote in message news:<ce******* *************** ***@posting.goo gle.com>... Hi. I want to create a trigger that only allows delete from table A if
corresponding record in table B does not exist. Any idea on how this
can be done? Thanks, Kenneth. ke************* **@telenor.com (Kenneth Osenbroch) wrote in message news:<ce******* *************** ***@posting.goo gle.com>... Hi. I want to create a trigger that only allows delete from table A if
corresponding record in table B does not exist. Any idea on how this
can be done? Thanks, Kenneth.
Sounds more like you want a reference constraint.
Do you have Primary keys and Foreign Keys set up on the corredsponding
tables? Looks like from the description table A is the parent table
(wiht a primary key) and table B is the child table (with a foreign
key that references the primary key of table A)
HTH,
ed ed********@magi cinterface.com (Ed prochak) wrote in message news:<4b******* *************** ****@posting.go ogle.com>... ke************* **@telenor.com (Kenneth Osenbroch) wrote in message news:<ce******* *************** ***@posting.goo gle.com>... Hi. I want to create a trigger that only allows delete from table A if
corresponding record in table B does not exist. Any idea on how this
can be done? Thanks, Kenneth.
Sounds more like you want a reference constraint.
Do you have Primary keys and Foreign Keys set up on the corredsponding
tables? Looks like from the description table A is the parent table
(wiht a primary key) and table B is the child table (with a foreign
key that references the primary key of table A)
HTH,
ed
Hi, and thanks for your reply.
The thing is that it is not possible to use constraints based on PK's
and FK's in this database (the relations are placed on the applicaton
layer - hence it doesn't exist any PK's or FK's).
So: I figure trigger is the only solution to ensure the above
scenario. Any ideas on how the trigger would look?
Thanks,
Kenneth ke************* **@telenor.com (Kenneth Osenbroch) wrote in message news:<ce******* *************** ****@posting.go ogle.com>... ed********@magi cinterface.com (Ed prochak) wrote in message news:<4b******* *************** ****@posting.go ogle.com>... ke************* **@telenor.com (Kenneth Osenbroch) wrote in message news:<ce******* *************** ***@posting.goo gle.com>... Hi. I want to create a trigger that only allows delete from table A if
corresponding record in table B does not exist. Any idea on how this
can be done? Thanks, Kenneth.
Sounds more like you want a reference constraint.
Do you have Primary keys and Foreign Keys set up on the corredsponding
tables? Looks like from the description table A is the parent table
(wiht a primary key) and table B is the child table (with a foreign
key that references the primary key of table A)
HTH,
ed
Hi, and thanks for your reply.
The thing is that it is not possible to use constraints based on PK's
and FK's in this database (the relations are placed on the applicaton
layer - hence it doesn't exist any PK's or FK's).
So: I figure trigger is the only solution to ensure the above
scenario. Any ideas on how the trigger would look?
Thanks,
Kenneth
I cannot think of any way for a trigger to STOP a delete, other than
maybe throwing an exception?
What do you mean the relations are in the application layer?
(CAUTION: That's the path to hell!)
Do you have two tables in the database or not?
It looks like you are using a screwdriver as a hammer. It doesn't work
well and in the end both the nail and the screwdriver are in bad
shape.
Sorry I cannot be more help, but I have a genetic disorder that
debilitates my programming skills when faced with an absurd
assignment. 8^)
Good luck! you are going to need it.
Ed ed********@magi cinterface.com (Ed prochak) wrote in message news:<4b******* *************** ****@posting.go ogle.com>... ke************* **@telenor.com (Kenneth Osenbroch) wrote in message news:<ce******* *************** ****@posting.go ogle.com>... ed********@magi cinterface.com (Ed prochak) wrote in message news:<4b******* *************** ****@posting.go ogle.com>... ke************* **@telenor.com (Kenneth Osenbroch) wrote in message news:<ce******* *************** ***@posting.goo gle.com>...
> Hi. I want to create a trigger that only allows delete from table A if
> corresponding record in table B does not exist. Any idea on how this
> can be done? Thanks, Kenneth.
Sounds more like you want a reference constraint.
Do you have Primary keys and Foreign Keys set up on the corredsponding
tables? Looks like from the description table A is the parent table
(wiht a primary key) and table B is the child table (with a foreign
key that references the primary key of table A)
HTH,
ed
Hi, and thanks for your reply.
The thing is that it is not possible to use constraints based on PK's
and FK's in this database (the relations are placed on the applicaton
layer - hence it doesn't exist any PK's or FK's).
So: I figure trigger is the only solution to ensure the above
scenario. Any ideas on how the trigger would look?
Thanks,
Kenneth
I cannot think of any way for a trigger to STOP a delete, other than
maybe throwing an exception?
What do you mean the relations are in the application layer?
(CAUTION: That's the path to hell!)
Do you have two tables in the database or not?
It looks like you are using a screwdriver as a hammer. It doesn't work
well and in the end both the nail and the screwdriver are in bad
shape.
Sorry I cannot be more help, but I have a genetic disorder that
debilitates my programming skills when faced with an absurd
assignment. 8^)
Good luck! you are going to need it.
Ed
:o)
I know! Consider the case closed.
Cheers,
Kenneth This thread has been closed and replies have been disabled. Please start a new discussion. Similar topics | |
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