Hello community,
I am a little bit confused by instead of update trigger logic.
Lets say there is a trigger MYTRIGGER which is an INSTEAD OF UPDATE trigger
that belongs to view named MYVIEW.
MYTRIGGER should update table MYTABLE with values sent from an application.
UPDATE MYTABLE
SET *primary = new . primary; *
* field2 = new . field2*,
*field3 = new . field3*
WHERE *primary = old.primary;*
So user decides to modify a record. He changes *primary, field2,
field3*values trough textboxes, and the app sends parametarised update
query to
sqlite engine.
UPDATE MYVIEW
SET *primary = @a*,
*field2 = @b*.
*field3 = @c*;
Since *primary* is not a surrogat key, and the user has changed it, there
is no way to and including it in a where clause.
My question is: does sqlite engine know the *old value of primary field*?
If yes, HOW? Is trigger executing once or for each row?
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