Question

这个SQL代码给了我错误＆＃34;错误在第2行：PL / SQL：语句被忽略＆＃34;，我正在研究SQL oracle application express / APEX：我尝试了我能想到的一切，它每次都给我不同的问题。

CREATE or replace TRIGGER remove_artista 
   instead of delete on V_ARTISTA
REFERENCING old AS orow
FOR EACH ROW
BEGIN
if exists(select * from Utilizadores where pessoaID = orow.pessoaID) then
        delete from Pessoas where pessoaID = orow.pessoaID;
ELSE
        delete from Artistas where pessoaID = orow.pessoaID;
        delete from Pessoas where pessoaID = orow.pessoaID;
end if;
END;

观点：

create or replace view v_artista as 
 select 
pessoaID, nome_p, sexo, data_nasc, nome_art, biografica
from Pessoas natural inner join Artistas;

编辑：修改了代码上的错字。

Answer 1

我从触发器收到的完整错误如下：

LINE/COL ERROR
-------- -----------------------------------------------------------------
2/1      PL/SQL: Statement ignored
2/4      PLS-00204: function or pseudo-column 'EXISTS' may be used inside
         a SQL statement only

基本上，问题是你不能像你一样说if exists(...)。甲骨文不允许你。

相反，请尝试将Utilizadores表中匹配的行数选择为局部变量，然后在if语句中使用该行：

CREATE or replace TRIGGER remove_artista 
   instead of delete on V_ARTISTA
REFERENCING old AS orow
FOR EACH ROW
DECLARE
  l_count       INTEGER;
BEGIN
  select count(*) 
    into l_count
    from Utilizadores
   where pessoaID = :orow.pessoaID;

  if l_count > 0 then
        delete from Pessoas where pessoaID = :orow.pessoaID;
  ELSE
        delete from Artistas where pessoaID = :orow.pessoaID;
        delete from Pessoas where pessoaID = :orow.pessoaID;
  end if;
END;

我还需要将orow替换为:orow。在进行此更改后，您的触发器也会为我编译。

Answer 2

我认为您不能使用IF EXISTS构造来检查是否存在行。您可以使用SELECT COUNT(*) INTO <a variable>。但是，您可能不需要检查是否存在行。以下代码可能会起作用：

CREATE OR REPLACE TRIGGER remove_artista 
INSTEAD OF DELETE ON V_ARTISTA
FOR EACH ROW
BEGIN
  DELETE FROM PESSOAS
  WHERE PESSOAID = :OLD.PESSOAID;

  DELETE FROM Artistas
  WHERE PESSOAID = :OLD.PESSOAID
  AND NOT EXISTS (SELECT 1 FROM UTILIZADORES WHERE PESSOAID = :OLD.PESSOAID);  

END;

任何情况下都会删除PESSOAS中的行。仅当ARTISTAS中不存在PESSOAID时，才会删除UTILIZADORES中的行。

<强>参考：

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sql oracle PL / SQL出错：语句被忽略

2 个答案: