create trigger

• With the compatibility level of 70 , the default behavior for create trigger is to add additional triggers to existing triggers if the trigger names differ
  如果触发器名称不同，则create trigger （兼容级别为70 ）的默认行为是在现有的触发器中添加其他触发器。
• However , if the compatibility level is equal to or less than 65 , any new triggers created by using the create trigger statement replace any existing triggers of the same type , even if the trigger names are different
  但是，如果兼容级别小于或等于65 ，那么，即使触发器名称不同，使用create trigger语句创建的任何新触发器都将替换同一类型的任何现有触发器。
• Allows the user to invoke a routine , create a function that is sourced from that routine applies to functions only , and to reference the routine in any ddl statement , such as create view , create trigger , or when defining a constraint
  允许用户调用例程，从例程创建函数（只应用于函数） ，以及在任何ddl语句（比如create view 、 create trigger或定义约束时）中引用例程
• Once a user is granted the execute privilege for a routine , the user can then invoke that routine , create a function that is sourced from that routine applies to functions only , and reference the routine in any ddl statement , such as create view or create trigger
  用户一旦被授予一个例程的execute特权，他就可以调用这个例程，从例程创建函数（只应用于函数） ，以及在任何ddl语句（比如create view或create trigger ）中引用例程。