The docs are really light on triggers (and functions and procedures).
Information about triggers in the reference guide is here and was
updated (slightly) for 10.1:
http://db.apache.org/derby/docs/10.1/ref/rrefsqlj43125.html
When implementing triggers, here are a couple things to keep in mind.
First, the body of the trigger can execute just one SQL statement.
Here's an example of someone who wrote a trigger that inserted data into
a shadow table, and used a CASE statement that needed some help to get
working (and I think the URL below points to the post that indicates
that problem was resolved):
http://mail-archives.apache.org/mod_mbox/db-derby-user/200508.mbox/[EMAIL
PROTECTED]
Next, a trigger can't execute a procedure, but it can execute a
function; however, functions are "read only" (can't update data in the
database). Here's one very simple example that shows the syntax for a
trigger that invokes a function implemented in Java:
http://mail-archives.apache.org/mod_mbox/db-derby-user/200506.mbox/[EMAIL
PROTECTED]
Often when I'm looking for an example on how to do something, I look at
the functional tests:
http://svn.apache.org/viewcvs.cgi/db/derby/code/trunk/java/testing/org/apache/derbyTesting/functionTests/tests/lang/
If none of this information helps, please feel free to post more
questions. I'm interested in this area and will try to assemble a more
helpful writeup on the topic that consolidates the information in all
these various posts.
-jean
Joachim G Stumpf wrote:
Hi,
i have to convert SQL Syntax to DERBY from Interbase.
I use Derby 10 and customer uses 10.1 . So i downloaded Alpha version of
reference Doku.
Now i have to define a trigger
Original
CREATE TRIGGER "ATV_tr1" FOR "tab1"
ACTIVE BEFORE INSERT POSITION 0
as
declare variable bId integer;
begin
select id_ from tab2 where bez_ = user into :bId;
if ( bId IS NULL ) then bId = 0;
new.xn_b_id_ = bId;
new.xad_b_id_ = bId;
new.neu_date_ = 'now';
new.aend_date_ = 'now';
end
;
I found db2 syntax which is similar to Derby.
create trigger atv_basis
no cascade before
insert on ADM_TR_VORGABE_BASIS
referencing new as new
for each row mode db2sql
begin atomic
set new.neu_datum_ = CURRENT_DATE;
set new.aend_datum_ = CURRENT_DATE;
end;
This isn't working too.
Can somebody help me out?
mfg
Joachim Stumpf DB2 Technical presales support
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