sql - PL/SQL触发触发问题

Question

我对PL / SQL触发器何时触发有疑问。

我写了以下触发器

CREATE OR REPLACE TRIGGER gradeInputCheck
BEFORE INSERT ON GRADE 
FOR EACH ROW
DECLARE
  newGrade GRADE.NUMERIC_GRADE%TYPE := :NEW.NUMERIC_GRADE;
    grade_too_low EXCEPTION;
    grade_too_high EXCEPTION;
BEGIN
  DBMS_OUTPUT.PUT_LINE(newGrade);
    IF (newGrade < 0) THEN
        RAISE grade_too_low;
    ELSIF (newGrade > 100) THEN
        RAISE grade_too_high;
    END IF;
EXCEPTION
    WHEN grade_too_low THEN
        DBMS_OUTPUT.PUT_LINE('Grades must be between 0 and 100');
    WHEN grade_too_high THEN
        DBMS_OUTPUT.PUT_LINE('Grades must be between 0 and 100');
END;

但是，当我运行一个简单的语句

UPDATE grade SET numeric_grade = -1;

触发器不触发。
关于如何使扳机开火有什么要点吗？

谢谢!

Answer 1

您的触发器是插入触发器。插入触发器不会触发更新语句。您应该改用以下方式:

BEFORE UPDATE ON GRADE