创建触发器引发异常

Question

我试图在插入表之前编写一个触发器.

它检查特定值,如果它无效,它将引发异常

CREATE OR REPLACE TRIGGER insert_birthdate
      BEFORE INSERT ON student 

DECLARE 
     invalid_date EXCEPTION ;
BEGIN
    IF(NEW.birthdate >= sysdate - interval '16' year )
    THEN RAISE invalid_date ;
    END IF ;
EXCEPTION
    WHEN invalid_date THEN
         RAISE_APPLICATION_ERROR(-20500, 'AGE MUST BE GREATER THAN 16 !!');
END;
/

这是行不通的.

这个输出,有什么帮助吗？

Warning: Trigger created with compilation errors.

SQL>
SQL> show errors
Errors for TRIGGER INSERT_BIRTHDATE:

LINE/COL ERROR
-------- ----------------------------------------------------------
4/2      PL/SQL: Statement ignored
4/8      PLS-00201: identifier 'NEW.BIRTHDATE' must be declared
SQL>

Answer 1

替换此行

IF(NEW.birthdate >= sysdate - interval '16' year )

同

IF(:NEW.birthdate >= sysdate - interval '16' year )

此外,您需要为每一行而不是整个语句执行before触发器.

来自Docs,

在BEFORE语句触发器中,触发器主体无法读取:NEW或:OLD.(在BEFORE行触发器中,触发器主体可以读取和写入:OLD和:NEW字段.)

就像这样

CREATE OR REPLACE TRIGGER orders_before_insert
BEFORE INSERT
   ON student
   FOR EACH ROW