create trigger\(em create a new trigger

.nf

\fBcreatetrigger\fR trigname\fB{before|after}\fP\fB{insert|update|delete}\fB

\fBon\fR relname\fBforeach{row|statement}\fR

\fBexecuteprocedure\fR funcname\fB(\fR arguments\fB)\fR

.fi

.BR"Create Trigger"

will enter a new trigger into the current data base. The trigger will be

associated with the relation

.IR relname

and will execute the specified

.IR funcname.

.PP

The trigger can be specified to fire either

.BR before

the operation is attempted on a tuple (e.g. before constraints are checked and

the insert/update/delete is attempted) or

.BR after

the operation has been attempted (e.g. after constraints are checked and the

insert/update/delete has completed).

If the trigger fires

.BR before

then the trigger may

skip the operation for the current tuple,

or change the current tuple (for insert/delete operations only).

If the trigger fires

.BR after

then all changes including the last insertion/updation/deletion

are "visible" to trigger.

.PP

Refer to the SPI and trigger programming guides for more information.

Examples are included in the contrib area of the source distribution.

drop trigger(l).

drop trigger\(em destroy existing classes

.nf

\fBdroptrigger\fR trigname

.fi

.BR"Drop Trigger"

removes triggers from the data base. Only its owner may destroy a

trigger.

.nf

--

--Destroy the empverify trigger

--

drop trigger empverify

.fi

create trigger(l).