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* 'retrieve into' in a rule?
@ 1994-05-09 14:59 keen@ms.uky.edu
1994-05-09 23:01 ` Re: 'retrieve into' in a rule? Paul M. Aoki <aoki@postgres.Berkeley.EDU>
0 siblings, 1 reply; 2+ messages in thread
From: keen@ms.uky.edu @ 1994-05-09 14:59 UTC (permalink / raw)
To: legacy
I am running with Postgres 4.2.
When I give a command to the monitor like
"retrieve into temp (emp.name) where emp.age = 40\g"
it works fine and creates the class temp with the info,
BUT if I put the same kind of command into a _rule_,
"define rule r5 is on
retrieve to emp.age where current.age ISNULL
do [retrieve into x (emp.all) where emp.dept= current.dept ] \g"
the rule is defined alright,
but when I actually try to retrieve from emp,
"retrieve (emp.all) \g"
I get a message that "type x already defined"
and no tuples are retrieved.
Suggestions?
Debby Keen
keen@ms.uky.edu
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^ permalink raw reply [nested|flat] 2+ messages in thread
* Re: 'retrieve into' in a rule?
1994-05-09 14:59 'retrieve into' in a rule? keen@ms.uky.edu
@ 1994-05-09 23:01 ` Paul M. Aoki <aoki@postgres.Berkeley.EDU>
0 siblings, 0 replies; 2+ messages in thread
From: Paul M. Aoki @ 1994-05-09 23:01 UTC (permalink / raw)
To: keen@ms.uky.edu; +Cc: legacy
keen@ms.uky.edu writes:
> "define rule r5 is on
> retrieve to emp.age where current.age ISNULL
> do [retrieve into x (emp.all) where emp.dept= current.dept ] \g"
> but when I actually try to retrieve from emp,
> "retrieve (emp.all) \g"
> I get a message that "type x already defined"
> and no tuples are retrieved.
so is this rule run more than once?
you're using the tuple-level rule system, so if there is more
than one emp with null age, the rule will be fired more than
once. of course, once the rule is fired, there's now an "x"
table and any following firings of the rule will blow out the
whole query (because "x" already exists).
seems like you should probably append to x (if you can do so).
--
Paul M. Aoki | CS Div., Dept. of EECS, UCB | aoki@postgres.Berkeley.EDU
| Berkeley, CA 94720 | ...!uunet!ucbvax!aoki
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