Oracle：在触发器中使用子查询

这个触发器可以做到：

CREATE OR REPLACe TRIGGER trigger_w_subqueryAFTER UPDATE OR INSERT ON project_archivingFOR EACH ROW WHEN (old.archiving_status <> new.archiving_status  AND new.archiving_status = 1)DECLARE  l_offer projects.offer%TYPE;BEGIN  SELECT offer INTO l_offer   FROM projects   WHERe projnum = :new.projnum;  IF l_offer IS NULL THEN    INSERT INTO offer_log (offer, status, date)    VALUES (null, 9, sysdate);  END IF;END;

我假设从项目中进行选择将始终找到一行；如果不是，它将引发您可能需要处理的NO_DATA_FOUND异常。