在插入pl / sql-oracle之前触发更新值

Question

this.parentForm.controls['question1'].valueChanges.subscribe(
    (selectedValue) => {
      console.log(selectedValue);
      console.log(this.parentForm.get('question1').value);     
    }
);

我想创建一个触发器，当我在表中插入4个主题的值时，它将自动计算百分比并设置奖学金折扣，如果学生 60％然后设置一些卢比折扣，如果<强于> 80％比设定一些卢比折扣

Answer 1

您需要编写简单的BEFORE INSERT触发器。你甚至不需要光标。尝试以下触发器。

CREATE OR REPLACE TRIGGER stud_percent_disc
BEFORE INSERT
ON student
FOR EACH ROW
  DECLARE
    v_total student.total%type;
    v_percent student.percentage%type;
    v_discount student.discount%type;
  BEGIN
    -- calculate total
    v_total := ( :new.s1 + :new.s2 + :new.s3 + :new.s4 );
    -- calculate percentage
    v_percent := ( v_total * 0.25 );
    -- calculate discount value
    if (v_percent >= 95) then
      v_discount := 25000;
    elsif (v_percent >= 90) then
      v_discount := 20000;
    elsif (v_percent >= 80) then
      v_discount := 15000;
    elsif (v_percent >= 75) then
      v_discount := 10000;
    else
      v_discount := 0;
    end if;
    :new.total := v_total;
    :new.percentage := v_percent;
    :new.discount := v_discount;
  END;
/

用户下面的插入语法：

insert into student(s1,s2,s3,s4,total,percentage,discount) values(88,88,88,88,0,0,0);