Question

我有两张桌子购买和客户，如果购买表中的购买时间（日期）与customers表中已有的last_visit（日期）不同，我需要在客户中更新visits_made（数字）。这是我正在尝试的触发器，我正在做一些非常可耻和错误的事情。

create or replace trigger update_visits_made
after insert on purchases
for each row
declare new_date purchases.ptime%type;

begin
  select ptime into new_date
    from purchases
  where purchases.ptime = :new.ptime;

  if new_date = customers.last_visit then
    new.last_visit=old.last_visit;
  else
    update customers 
      set visits_made=visits_made+1
    where purchases.ptime=:new.ptime;
  end if;
end;
/
show errors

有人可以告诉我哪里出错了吗？

我收到以下错误 LINE / COL ERROR

10/15 PLS-00103：当期待其中一个时遇到符号“=”            以下：            ：=。（@％;

11/1 PLS-00103：遇到符号“ELSE”

16/1 PLS-00103：遇到符号“END”

Answer 1

这是PL / SQL中的标量赋值：

new.last_visit = old.last_visit;

不仅应该使用:=，而且new和old应该在其名称前加冒号：

:new.last_visit := :old.last_visit;

修复该问题后，update会出现问题：

update customers 
    set visits_made=visits_made+1
    where purchases.ptime = :new.ptime;

我不清楚这应该是做什么的，所以我不能提出任何建议，除了指出purchases没有被定义。

Answer 2

I think somehow i get your requirement. Basically its a ticker which count the vists of user based on Login dates. I have written a snippet below which replicates the same scenario as mentioned Above. Let me know if this helps.

-- Table creation and insertion script
CREATE TABLE PURCHASES
(
P_ID NUMBER,
P_TIME DATE
);

INSERT INTO PURCHASES
SELECT LEVEL,SYSDATE+LEVEL FROM DUAL
CONNECT BY LEVEL < 10;

CREATE TABLE CUSTOMERS
(
P_ID NUMBER,
P_VISITS NUMBER
);

INSERT INTO CUSTOMERS
SELECT LEVEL,NULL FROM DUAL
CONNECT BY LEVEL < 10;

-- Table creation and insertion script

--Trigger Script

CREATE OR REPLACE TRIGGER update_purchase BEFORE
  INSERT ON purchases FOR EACH row 
  DECLARE 
  new_date purchases.p_time%type;
  BEGIN
  BEGIN
  SELECT A.P_TIME
    INTO new_date
    FROM
  (SELECT p_time,
    ROW_NUMBER() OVER(PARTITION BY P_ID ORDER BY P_TIME DESC) RNK
    --    INTO new_date
  FROM purchases
  WHERE purchases.p_id = :new.p_id
  )a
WHERE A.RNK =1;
    EXCEPTION WHEN OTHERS THEN
    RETURN;
    END;
IF :NEW.P_TIME <> new_date THEN
  UPDATE customers
  SET P_VISITS        =NVL(P_VISITS,0)+1
  WHERE p_id=:new.p_id;
END IF;
END;

--Trigger Script


--Testing Script
INSERT INTO PURCHASES VALUES
(9,TO_DATE('12/11/2015','MM/DD/YYYY'));

--Testing Script

涉及2个表的触发器中的PLSQL条件语句

2 个答案: