Under what conditions would a Sybase trigger not be called?

Question

I have a couple of triggers in a Sybase ASE database that are fired upon updates to two tables: Docs and Trans.

The triggers are defined as shown here:

For Docs:

 CREATE TRIGGER dbo.Index_Change_Docs
 ON dbo.docs
 FOR INSERT,UPDATE AS

 IF UPDATE(DOCTYPE) OR UPDATE(BATCH_NO) OR UPDATE(SCANDATE) OR           
 UPDATE(PERIOD_START_DATE) OR UPDATE(PERIOD_END_DATE) 
 OR UPDATE(DISPATCH_ID) OR UPDATE(DISPATCH_NAME) OR UPDATE(CHECKNUM) OR    
 UPDATE(CHECKAMT)
 BEGIN
    INSERT INTO 
    DOCID_SYNC (IS_DOC_ID, CRTN_DT, SYNC_STATUS_CDE) 
    SELECT Inserted.DOCID, GETDATE(), "N" FROM Inserted

 END

For Trans:

 CREATE TRIGGER dbo.Index_Change_Trans
 ON dbo.Trans
 FOR INSERT,UPDATE AS

 IF UPDATE(TRANSNUM) OR UPDATE(CONTRACT) OR UPDATE(FRANCHISE) OR UPDATE(SSN) OR      
 UPDATE(STATE_CODE) OR UPDATE(TRANSTYPE)
OR UPDATE(AGENCYNUM) OR UPDATE(LOCKBOXBATCHNUM) OR UPDATE(PRODUCTCODE) 
 BEGIN

    INSERT INTO 
    DOCID_SYNC (IS_DOC_ID, CRTN_DT, SYNC_STATUS_CDE)
    SELECT DOCID, GETDATE(), "N" FROM DOCS
    WHERE Transnum = (SELECT Inserted.TransNum from Inserted)
 END

It appears the behavior of these triggers is different, depending on how updates to those tables are made.

In one case, these tables are updated via two stored procedures (Insert_Docs_SP and Insert_Trans_SP). When this happens, each trigger is fired once (once for Docs, one for Trans) and everything works as expected.

In another case, these tables are updated within a Sybase transaction with two database updates. Here, the first update is done via inline SQL in the calling application (which fires the Trans trigger.) The second update is done via a stored procedure - Insert_Docs_SP, the same as in the other case - which does not fire a trigger.

Perhaps there is something about how transactions are handled that I am not understanding?

Answer 1

I found the answer - it's in the order of execution. I thought one of the triggers wasn't being fired - in this case the Index_Change_Trans trigger - but in fact it was. I didn't see the results, however, because this trigger is relying on entries in the Docs table.

INSERT INTO 
DOCID_SYNC (IS_DOC_ID, CRTN_DT, SYNC_STATUS_CDE)
SELECT DOCID, GETDATE(), "N" FROM DOCS
WHERE Transnum = (SELECT Inserted.TransNum from Inserted)

So, in cases where the Trans table was updated before the Docs table, the run of the Trans trigger would not show an update in the Docid_Sync table - since at this point there were no entries in the Docs table with the appropriate Transnum value. In these cases, the Docid_Sync table only has one entry, the result of the Docs trigger.

In other instances, the Docs table is updated first, and then the Trans table. In these instances, the Docid_Sync table has two entries - one as the result of the Docs trigger, and another as the result of the Trans trigger.

Answer 2

In both of your triggers, the trigger is only inserting into docid_sync table if certain columns are updated. Are you sure that the stored procedure is updating one of the columns in the trigger? Triggers are also not called if it is a recursive update from a trigger call, but that doesn't seem to be the case here.

The other possibility is if the calling transaction disabled the trigger with the set triggers off command. I would start with ensuring that the stored procedure is updating one of the columns in the trigger checks.

One other question: Is the same row being updated twice, in the inline SQL And stored procedure in your error case, or are they updating two different rows?