Instead of triggers in oracle database are defined on views only. A normal DML trigger executes only when a DML operation is issued on a table.Whereas instead of trigger fires when a DML statment is issued on the view. Instead-of triggers must be row level. Create Instead of Trigger-Example :Take a look at the following view defintion: As the view consists of two table joins, it is illegal to insert records into this view as the insert requires both the underlying tables to be modified.nstead-of triggers must be row level. Create Instead of Trigger-Example : Take a look at the following view defintion: As the view consists of two table joins, it is illegal to insert records into this view as the insert requires both the underlying tables to be modified.