如果触发器上没有数据，如何抛出错误

Question

我想在触发器上找不到数据时抛出一个错误，所以我使用了以下触发器。当第一次没有找到数据时工作，此后数据prsents它不工作且没有结果发生。关于这个问题的任何想法

    create or replace 
    trigger testtrigger
    after INSERT OR UPDATE 
    on T1
    FOR EACH ROW 
    BEGIN
     SELECT t_power
        INTO t_power_trg
        FROM t3
        WHERE UPPER(t3.NAME) LIKE ('%' || UPPER(:NEW.INFO) || '%'); 
        EXCEPTION
      WHEN NO_DATA_FOUND THEN
      RAISE_APPLICATION_ERROR(-20001,'-------------Selected  model is  not present (info(2))-------------');
  SELECT refer_power
        INTO refer_power_trg
        FROM t3
        WHERE UPPER(t3.NAME) LIKE ('%' || UPPER(:NEW.TAR2) || '%'); 
        EXCEPTION
      WHEN NO_DATA_FOUND THEN
      RAISE_APPLICATION_ERROR(-20001,'-------------Selected  reference is  not present (info(2))-------------');

      UPDATE t_master
      SET 
       Master_pwr=t_power_trg where firstname='Z'
    END IF;
    END

Answer 1

您的代码中存在一些SYNTAX问题，请查看以下代码。希望它能满足您的要求。

    CREATE OR REPLACE TRIGGER testtrigger
    AFTER INSERT OR UPDATE ON T1
    FOR EACH ROW 
    DECLARE 
      t_power_trg T3.T_POWER%TYPE;
    BEGIN
    SELECT t_power
      INTO t_power_trg
      FROM t3
     WHERE UPPER(t3.NAME) LIKE ('%' || UPPER(:NEW.INFO) || '%');

    UPDATE t_master
       SET Master_pwr=t_power_trg
     where firstname='Z';

    EXCEPTION
      WHEN NO_DATA_FOUND THEN
         RAISE_APPLICATION_ERROR(-20001,'-------------Selected  model is  not present (info(2))-------------');
    END;

Answer 2

这是一个函数，您可以在循环之前添加一个步骤来捕获您想要查看的案例数

像这样：

if ((select count(*)
       FROM t3
      WHERE UPPER(t3.NAME) LIKE ('%' || UPPER(:NEW.INFO) || '%')) < 1
    ) then
SET @error = '-------------Selected  model is  not present (info(2))-------------';
end if;